Ruff

An extremely fast Python linter, written in Rust.

Shows a bar chart with benchmark results.

Linting the CPython codebase from scratch.

⚡️ 10-100x faster than existing linters
🐍 Installable via pip
🤝 Python 3.11 compatibility
🛠️ pyproject.toml support
📦 Built-in caching, to avoid re-analyzing unchanged files
🔧 Autofix support, for automatic error correction (e.g., automatically remove unused imports)
⚖️ Near-parity with the built-in Flake8 rule set
🔌 Native re-implementations of dozens of Flake8 plugins, like flake8-bugbear
⌨️ First-party editor integrations for VS Code and more
🌎 Monorepo-friendly, with hierarchical and cascading configuration

Ruff aims to be orders of magnitude faster than alternative tools while integrating more functionality behind a single, common interface.

Ruff can be used to replace Flake8 (plus a variety of plugins), isort, pydocstyle, yesqa, eradicate, pyupgrade, and autoflake, all while executing tens or hundreds of times faster than any individual tool.

Ruff goes beyond the responsibilities of a traditional linter, instead functioning as an advanced code transformation tool capable of upgrading type annotations, rewriting class definitions, sorting imports, and more.

Ruff is extremely actively developed and used in major open-source projects like:

Read the launch blog post.

Testimonials

Sebastián Ramírez, creator of FastAPI:

Ruff is so fast that sometimes I add an intentional bug in the code just to confirm it's actually running and checking the code.

Bryan Van de Ven, co-creator of Bokeh, original author of Conda:

Ruff is ~150-200x faster than flake8 on my machine, scanning the whole repo takes ~0.2s instead of ~20s. This is an enormous quality of life improvement for local dev. It's fast enough that I added it as an actual commit hook, which is terrific.

Tim Abbott, lead developer of Zulip:

This is just ridiculously fast... ruff is amazing.

Installation and Usage

Installation

Ruff is available as ruff on PyPI:

pip install ruff

For macOS Homebrew and Linuxbrew users, Ruff is also available as ruff on Homebrew:

brew install ruff

For Conda users, Ruff is also available as ruff on conda-forge:

conda install -c conda-forge ruff

For Arch Linux users, Ruff is also available as ruff on the official repositories:

pacman -S ruff

Usage

To run Ruff, try any of the following:

ruff path/to/code/to/check.py  # Run Ruff over `check.py`
ruff path/to/code/             # Run Ruff over all files in `/path/to/code` (and any subdirectories)
ruff path/to/code/*.py         # Run Ruff over all `.py` files in `/path/to/code`

You can run Ruff in --watch mode to automatically re-run on-change:

ruff path/to/code/ --watch

Ruff also works with pre-commit:

- repo: https://github.com/charliermarsh/ruff-pre-commit
  # Ruff version.
  rev: 'v0.0.208'
  hooks:
    - id: ruff
      # Respect `exclude` and `extend-exclude` settings.
      args: ["--force-exclude"]

Configuration

Ruff is configurable both via pyproject.toml and the command line. For a full list of configurable options, see the API reference.

If left unspecified, the default configuration is equivalent to:

[tool.ruff]
line-length = 88

# Enable Pyflakes `E` and `F` codes by default.
select = ["E", "F"]
ignore = []

# Exclude a variety of commonly ignored directories.
exclude = [
    ".bzr",
    ".direnv",
    ".eggs",
    ".git",
    ".hg",
    ".mypy_cache",
    ".nox",
    ".pants.d",
    ".ruff_cache",
    ".svn",
    ".tox",
    ".venv",
    "__pypackages__",
    "_build",
    "buck-out",
    "build",
    "dist",
    "node_modules",
    "venv",
]
per-file-ignores = {}

# Allow unused variables when underscore-prefixed.
dummy-variable-rgx = "^(_+|(_+[a-zA-Z0-9_]*[a-zA-Z0-9]+?))$"

# Assume Python 3.10.
target-version = "py310"

[tool.ruff.mccabe]
# Unlike Flake8, default to a complexity level of 10.
max-complexity = 10

As an example, the following would configure Ruff to: (1) avoid checking for line-length violations (E501); (2) never remove unused imports (F401); and (3) ignore import-at-top-of-file errors (E402) in __init__.py files:

[tool.ruff]
# Enable Pyflakes and pycodestyle rules.
select = ["E", "F"]

# Never enforce `E501` (line length violations).
ignore = ["E501"]

# Never try to fix `F401` (unused imports).
unfixable = ["F401"]

# Ignore `E402` (import violations) in all `__init__.py` files, and in `path/to/file.py`.
[tool.ruff.per-file-ignores]
"__init__.py" = ["E402"]
"path/to/file.py" = ["E402"]

Plugin configurations should be expressed as subsections, e.g.:

[tool.ruff]
# Add "Q" to the list of enabled codes.
select = ["E", "F", "Q"]

[tool.ruff.flake8-quotes]
docstring-quotes = "double"

Ruff mirrors Flake8's error code system, in which each error code consists of a one-to-three letter prefix, followed by three digits (e.g., F401). The prefix indicates that "source" of the error code (e.g., F for Pyflakes, E for pycodestyle, ANN for flake8-annotations). The set of enabled errors is determined by the select and ignore options, which support both the full error code (e.g., F401) and the prefix (e.g., F).

As a special-case, Ruff also supports the ALL error code, which enables all error codes. Note that some of the pydocstyle error codes are conflicting (e.g., D203 and D211) as they represent alternative docstring formats. Enabling ALL without further configuration may result in suboptimal behavior, especially for the pydocstyle plugin.

As an alternative to pyproject.toml, Ruff will also respect a ruff.toml file, which implements an equivalent schema (though the [tool.ruff] hierarchy can be omitted). For example, the above pyproject.toml described above would be represented via the following ruff.toml:

# Enable Pyflakes and pycodestyle rules.
select = ["E", "F"]

# Never enforce `E501` (line length violations).
ignore = ["E501"]

# Always autofix, but never try to fix `F401` (unused imports).
fix = true
unfixable = ["F401"]

# Ignore `E402` (import violations) in all `__init__.py` files, and in `path/to/file.py`.
[per-file-ignores]
"__init__.py" = ["E402"]
"path/to/file.py" = ["E402"]

For a full list of configurable options, see the API reference.

Some common configuration settings can be provided via the command-line:

ruff path/to/code/ --select F401 --select F403

See ruff --help for more:

Ruff: An extremely fast Python linter.

Usage: ruff [OPTIONS] [FILES]...

Arguments:
  [FILES]...

Options:
      --config <CONFIG>
          Path to the `pyproject.toml` or `ruff.toml` file to use for configuration
  -v, --verbose
          Enable verbose logging
  -q, --quiet
          Only log errors
  -s, --silent
          Disable all logging (but still exit with status code "1" upon detecting errors)
  -e, --exit-zero
          Exit with status code "0", even upon detecting errors
  -w, --watch
          Run in watch mode by re-running whenever files change
      --fix
          Attempt to automatically fix lint errors
      --fix-only
          Fix any fixable lint errors, but don't report on leftover violations. Implies `--fix`
      --diff
          Avoid writing any fixed files back; instead, output a diff for each changed file to stdout
  -n, --no-cache
          Disable cache reads
      --select <SELECT>
          Comma-separated list of error codes to enable (or ALL, to enable all checks)
      --extend-select <EXTEND_SELECT>
          Like --select, but adds additional error codes on top of the selected ones
      --ignore <IGNORE>
          Comma-separated list of error codes to disable
      --extend-ignore <EXTEND_IGNORE>
          Like --ignore, but adds additional error codes on top of the ignored ones
      --exclude <EXCLUDE>
          List of paths, used to exclude files and/or directories from checks
      --extend-exclude <EXTEND_EXCLUDE>
          Like --exclude, but adds additional files and directories on top of the excluded ones
      --fixable <FIXABLE>
          List of error codes to treat as eligible for autofix. Only applicable when autofix itself is enabled (e.g., via `--fix`)
      --unfixable <UNFIXABLE>
          List of error codes to treat as ineligible for autofix. Only applicable when autofix itself is enabled (e.g., via `--fix`)
      --per-file-ignores <PER_FILE_IGNORES>
          List of mappings from file pattern to code to exclude
      --format <FORMAT>
          Output serialization format for error messages [possible values: text, json, junit, grouped, github, gitlab]
      --stdin-filename <STDIN_FILENAME>
          The name of the file when passing it through stdin
      --cache-dir <CACHE_DIR>
          Path to the cache directory
      --show-source
          Show violations with source code
      --respect-gitignore
          Respect file exclusions via `.gitignore` and other standard ignore files
      --force-exclude
          Enforce exclusions, even for paths passed to Ruff directly on the command-line
      --update-check
          Enable or disable automatic update checks
      --dummy-variable-rgx <DUMMY_VARIABLE_RGX>
          Regular expression matching the name of dummy variables
      --target-version <TARGET_VERSION>
          The minimum Python version that should be supported
      --line-length <LINE_LENGTH>
          Set the line-length for length-associated checks and automatic formatting
      --max-complexity <MAX_COMPLEXITY>
          Maximum McCabe complexity allowed for a given function
      --add-noqa
          Enable automatic additions of `noqa` directives to failing lines
      --clean
          Clear any caches in the current directory or any subdirectories
      --explain <EXPLAIN>
          Explain a rule
      --show-files
          See the files Ruff will be run against with the current settings
      --show-settings
          See the settings Ruff will use to check a given Python file
  -h, --help
          Print help information
  -V, --version
          Print version information

`pyproject.toml` discovery

Similar to ESLint, Ruff supports hierarchical configuration, such that the "closest" pyproject.toml file in the directory hierarchy is used for every individual file, with all paths in the pyproject.toml file (e.g., exclude globs, src paths) being resolved relative to the directory containing the pyproject.toml file.

There are a few exceptions to these rules:

In locating the "closest" pyproject.toml file for a given path, Ruff ignore any pyproject.toml files that lack a [tool.ruff] section.
If a configuration file is passed directly via --config, those settings are used for across files. Any relative paths in that configuration file (like exclude globs or src paths) are resolved relative to the current working directory.
If no pyproject.toml file is found in the filesystem hierarchy, Ruff will fall back to using a default configuration. If a user-specific configuration file exists at ${config_dir}/ruff/pyproject.toml, that file will be used instead of the default configuration, with ${config_dir} being determined via the dirs crate, and all relative paths being again resolved relative to the current working directory.
Any pyproject.toml-supported settings that are provided on the command-line (e.g., via --select) will override the settings in every resolved configuration file.

Unlike ESLint, Ruff does not merge settings across configuration files; instead, the "closest" configuration file is used, and any parent configuration files are ignored. In lieu of this implicit cascade, Ruff supports an extend field, which allows you to inherit the settings from another pyproject.toml file, like so:

# Extend the `pyproject.toml` file in the parent directory.
extend = "../pyproject.toml"
# But use a different line length.
line-length = 100

All of the above rules apply equivalently to ruff.toml files. If Ruff detects both a ruff.toml and pyproject.toml file, it will defer to the ruff.toml.

Python file discovery

When passed a path on the command-line, Ruff will automatically discover all Python files in that path, taking into account the exclude and extend-exclude settings in each directory's pyproject.toml file.

By default, Ruff will also skip any files that are omitted via .ignore, .gitignore, .git/info/exclude, and global gitignore files (see: respect-gitignore).

Files that are passed to ruff directly are always checked, regardless of the above criteria. For example, ruff /path/to/excluded/file.py will always check file.py.

Ignoring errors

To omit a lint check entirely, add it to the "ignore" list via ignore or extend-ignore, either on the command-line or in your project.toml file.

To ignore an error inline, Ruff uses a noqa system similar to Flake8. To ignore an individual error, add # noqa: {code} to the end of the line, like so:

# Ignore F841.
x = 1  # noqa: F841

# Ignore E741 and F841.
i = 1  # noqa: E741, F841

# Ignore _all_ errors.
x = 1  # noqa

Note that, for multi-line strings, the noqa directive should come at the end of the string, and will apply to the entire string, like so:

"""Lorem ipsum dolor sit amet.

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
"""  # noqa: E501

To ignore all errors across an entire file, Ruff supports Flake8's # flake8: noqa directive (or, equivalently, # ruff: noqa). Adding either of those directives to any part of a file will disable error reporting for the entire file.

For targeted exclusions across entire files (e.g., "Ignore all F841 violations in /path/to/file.py"), see the per-file-ignores configuration setting.

"Action Comments"

Ruff respects isort's "Action Comments" (# isort: skip_file, # isort: on, # isort: off, # isort: skip, and # isort: split), which enable selectively enabling and disabling import sorting for blocks of code and other inline configuration.

See the isort documentation for more.

Automating `noqa` Directives

Ruff supports several workflows to aid in noqa management.

First, Ruff provides a special error code, RUF100, to enforce that your noqa directives are "valid", in that the errors they say they ignore are actually being triggered on that line (and thus suppressed). You can run ruff /path/to/file.py --extend-select RUF100 to flag unused noqa directives.

Second, Ruff can automatically remove unused noqa directives via its autofix functionality. You can run ruff /path/to/file.py --extend-select RUF100 --fix to automatically remove unused noqa directives.

Third, Ruff can automatically add noqa directives to all failing lines. This is useful when migrating a new codebase to Ruff. You can run ruff /path/to/file.py --add-noqa to automatically add noqa directives to all failing lines, with the appropriate error codes.

Supported Rules

Regardless of the rule's origin, Ruff re-implements every rule in Rust as a first-party feature.

By default, Ruff enables all E and F error codes, which correspond to those built-in to Flake8.

The 🛠 emoji indicates that a rule is automatically fixable by the --fix command-line option.

Pyflakes (F)

For more, see Pyflakes on PyPI.

Code	Name	Message	Fix
F401	UnusedImport	`...` imported but unused	🛠
F402	ImportShadowedByLoopVar	Import `...` from line 1 shadowed by loop variable
F403	ImportStarUsed	`from ... import *` used; unable to detect undefined names
F404	LateFutureImport	`from __future__` imports must occur at the beginning of the file
F405	ImportStarUsage	`...` may be undefined, or defined from star imports: `...`
F406	ImportStarNotPermitted	`from ... import *` only allowed at module level
F407	FutureFeatureNotDefined	Future feature `...` is not defined
F501	PercentFormatInvalidFormat	'...' % ... has invalid format string: ...
F502	PercentFormatExpectedMapping	'...' % ... expected mapping but got sequence
F503	PercentFormatExpectedSequence	'...' % ... expected sequence but got mapping
F504	PercentFormatExtraNamedArguments	'...' % ... has unused named argument(s): ...	🛠
F505	PercentFormatMissingArgument	'...' % ... is missing argument(s) for placeholder(s): ...
F506	PercentFormatMixedPositionalAndNamed	'...' % ... has mixed positional and named placeholders
F507	PercentFormatPositionalCountMismatch	'...' % ... has 4 placeholder(s) but 2 substitution(s)
F508	PercentFormatStarRequiresSequence	'...' % ... `*` specifier requires sequence
F509	PercentFormatUnsupportedFormatCharacter	'...' % ... has unsupported format character 'c'
F521	StringDotFormatInvalidFormat	'...'.format(...) has invalid format string: ...
F522	StringDotFormatExtraNamedArguments	'...'.format(...) has unused named argument(s): ...	🛠
F523	StringDotFormatExtraPositionalArguments	'...'.format(...) has unused arguments at position(s): ...
F524	StringDotFormatMissingArguments	'...'.format(...) is missing argument(s) for placeholder(s): ...
F525	StringDotFormatMixingAutomatic	'...'.format(...) mixes automatic and manual numbering
F541	FStringMissingPlaceholders	f-string without any placeholders	🛠
F601	MultiValueRepeatedKeyLiteral	Dictionary key literal repeated
F602	MultiValueRepeatedKeyVariable	Dictionary key `...` repeated
F621	ExpressionsInStarAssignment	Too many expressions in star-unpacking assignment
F622	TwoStarredExpressions	Two starred expressions in assignment
F631	AssertTuple	Assert test is a non-empty tuple, which is always `True`
F632	IsLiteral	Use `==` to compare constant literals	🛠
F633	InvalidPrintSyntax	Use of `>>` is invalid with `print` function
F634	IfTuple	If test is a tuple, which is always `True`
F701	BreakOutsideLoop	`break` outside loop
F702	ContinueOutsideLoop	`continue` not properly in loop
F704	YieldOutsideFunction	`yield` statement outside of a function
F706	ReturnOutsideFunction	`return` statement outside of a function/method
F707	DefaultExceptNotLast	An `except` block as not the last exception handler
F722	ForwardAnnotationSyntaxError	Syntax error in forward annotation: `...`
F811	RedefinedWhileUnused	Redefinition of unused `...` from line 1
F821	UndefinedName	Undefined name `...`
F822	UndefinedExport	Undefined name `...` in `__all__`
F823	UndefinedLocal	Local variable `...` referenced before assignment
F841	UnusedVariable	Local variable `...` is assigned to but never used
F842	UnusedAnnotation	Local variable `...` is annotated but never used
F901	RaiseNotImplemented	`raise NotImplemented` should be `raise NotImplementedError`	🛠

pycodestyle (E, W)

For more, see pycodestyle on PyPI.

Code	Name	Message	Fix
E401	MultipleImportsOnOneLine	Multiple imports on one line
E402	ModuleImportNotAtTopOfFile	Module level import not at top of file
E501	LineTooLong	Line too long (89 > 88 characters)
E711	NoneComparison	Comparison to `None` should be `cond is None`	🛠
E712	TrueFalseComparison	Comparison to `True` should be `cond is True`	🛠
E713	NotInTest	Test for membership should be `not in`	🛠
E714	NotIsTest	Test for object identity should be `is not`	🛠
E721	TypeComparison	Do not compare types, use `isinstance()`
E722	DoNotUseBareExcept	Do not use bare `except`
E731	DoNotAssignLambda	Do not assign a `lambda` expression, use a `def`	🛠
E741	AmbiguousVariableName	Ambiguous variable name: `...`
E742	AmbiguousClassName	Ambiguous class name: `...`
E743	AmbiguousFunctionName	Ambiguous function name: `...`
E902	IOError	IOError: `...`
E999	SyntaxError	SyntaxError: `...`
W292	NoNewLineAtEndOfFile	No newline at end of file	🛠
W605	InvalidEscapeSequence	Invalid escape sequence: '\c'	🛠

mccabe (C90)

For more, see mccabe on PyPI.

Code	Name	Message	Fix
C901	FunctionIsTooComplex	`...` is too complex (10)

isort (I)

For more, see isort on PyPI.

Code	Name	Message	Fix
I001	UnsortedImports	Import block is un-sorted or un-formatted	🛠

pydocstyle (D)

For more, see pydocstyle on PyPI.

Code	Name	Message	Fix
D100	PublicModule	Missing docstring in public module
D101	PublicClass	Missing docstring in public class
D102	PublicMethod	Missing docstring in public method
D103	PublicFunction	Missing docstring in public function
D104	PublicPackage	Missing docstring in public package
D105	MagicMethod	Missing docstring in magic method
D106	PublicNestedClass	Missing docstring in public nested class
D107	PublicInit	Missing docstring in `__init__`
D200	FitsOnOneLine	One-line docstring should fit on one line
D201	NoBlankLineBeforeFunction	No blank lines allowed before function docstring (found 1)	🛠
D202	NoBlankLineAfterFunction	No blank lines allowed after function docstring (found 1)	🛠
D203	OneBlankLineBeforeClass	1 blank line required before class docstring	🛠
D204	OneBlankLineAfterClass	1 blank line required after class docstring	🛠
D205	BlankLineAfterSummary	1 blank line required between summary line and description	🛠
D206	IndentWithSpaces	Docstring should be indented with spaces, not tabs
D207	NoUnderIndentation	Docstring is under-indented	🛠
D208	NoOverIndentation	Docstring is over-indented	🛠
D209	NewLineAfterLastParagraph	Multi-line docstring closing quotes should be on a separate line	🛠
D210	NoSurroundingWhitespace	No whitespaces allowed surrounding docstring text	🛠
D211	NoBlankLineBeforeClass	No blank lines allowed before class docstring	🛠
D212	MultiLineSummaryFirstLine	Multi-line docstring summary should start at the first line
D213	MultiLineSummarySecondLine	Multi-line docstring summary should start at the second line
D214	SectionNotOverIndented	Section is over-indented ("Returns")	🛠
D215	SectionUnderlineNotOverIndented	Section underline is over-indented ("Returns")	🛠
D300	UsesTripleQuotes	Use """triple double quotes"""
D301	UsesRPrefixForBackslashedContent	Use r""" if any backslashes in a docstring
D400	EndsInPeriod	First line should end with a period	🛠
D402	NoSignature	First line should not be the function's signature
D403	FirstLineCapitalized	First word of the first line should be properly capitalized
D404	NoThisPrefix	First word of the docstring should not be "This"
D405	CapitalizeSectionName	Section name should be properly capitalized ("returns")	🛠
D406	NewLineAfterSectionName	Section name should end with a newline ("Returns")	🛠
D407	DashedUnderlineAfterSection	Missing dashed underline after section ("Returns")	🛠
D408	SectionUnderlineAfterName	Section underline should be in the line following the section's name ("Returns")	🛠
D409	SectionUnderlineMatchesSectionLength	Section underline should match the length of its name ("Returns")	🛠
D410	BlankLineAfterSection	Missing blank line after section ("Returns")	🛠
D411	BlankLineBeforeSection	Missing blank line before section ("Returns")	🛠
D412	NoBlankLinesBetweenHeaderAndContent	No blank lines allowed between a section header and its content ("Returns")	🛠
D413	BlankLineAfterLastSection	Missing blank line after last section ("Returns")	🛠
D414	NonEmptySection	Section has no content ("Returns")
D415	EndsInPunctuation	First line should end with a period, question mark, or exclamation point	🛠
D416	SectionNameEndsInColon	Section name should end with a colon ("Returns")	🛠
D417	DocumentAllArguments	Missing argument descriptions in the docstring: `x`, `y`
D418	SkipDocstring	Function decorated with `@overload` shouldn't contain a docstring
D419	NonEmpty	Docstring is empty

pyupgrade (UP)

For more, see pyupgrade on PyPI.

Code	Name	Message	Fix
UP001	UselessMetaclassType	`__metaclass__ = type` is implied	🛠
UP003	TypeOfPrimitive	Use `str` instead of `type(...)`	🛠
UP004	UselessObjectInheritance	Class `...` inherits from `object`	🛠
UP005	DeprecatedUnittestAlias	`assertEquals` is deprecated, use `assertEqual`	🛠
UP006	UsePEP585Annotation	Use `list` instead of `List` for type annotations	🛠
UP007	UsePEP604Annotation	Use `X \| Y` for type annotations	🛠
UP008	SuperCallWithParameters	Use `super()` instead of `super(__class__, self)`	🛠
UP009	PEP3120UnnecessaryCodingComment	UTF-8 encoding declaration is unnecessary	🛠
UP010	UnnecessaryFutureImport	Unnecessary `__future__` import `...` for target Python version	🛠
UP011	UnnecessaryLRUCacheParams	Unnecessary parameters to `functools.lru_cache`	🛠
UP012	UnnecessaryEncodeUTF8	Unnecessary call to `encode` as UTF-8	🛠
UP013	ConvertTypedDictFunctionalToClass	Convert `...` from `TypedDict` functional to class syntax	🛠
UP014	ConvertNamedTupleFunctionalToClass	Convert `...` from `NamedTuple` functional to class syntax	🛠
UP015	RedundantOpenModes	Unnecessary open mode parameters	🛠
UP016	RemoveSixCompat	Unnecessary `six` compatibility usage	🛠
UP017	DatetimeTimezoneUTC	Use `datetime.UTC` alias	🛠
UP018	NativeLiterals	Unnecessary call to `str`	🛠
UP019	TypingTextStrAlias	`typing.Text` is deprecated, use `str`	🛠
UP020	OpenAlias	Use builtin `open`	🛠
UP021	ReplaceUniversalNewlines	`universal_newlines` is deprecated, use `text`	🛠
UP022	ReplaceStdoutStderr	Sending stdout and stderr to pipe is deprecated, use `capture_output`	🛠
UP023	RewriteCElementTree	`cElementTree` is deprecated, use `ElementTree`	🛠
UP024	OSErrorAlias	Replace aliased errors with `OSError`	🛠
UP025	RewriteUnicodeLiteral	Remove unicode literals from strings	🛠
UP026	RewriteMockImport	`mock` is deprecated, use `unittest.mock`	🛠
UP027	RewriteListComprehension	Replace unpacked list comprehension with a generator expression	🛠

pep8-naming (N)

For more, see pep8-naming on PyPI.

Code	Name	Message
N801	InvalidClassName	Class name `...` should use CapWords convention
N802	InvalidFunctionName	Function name `...` should be lowercase
N803	InvalidArgumentName	Argument name `...` should be lowercase
N804	InvalidFirstArgumentNameForClassMethod	First argument of a class method should be named `cls`
N805	InvalidFirstArgumentNameForMethod	First argument of a method should be named `self`
N806	NonLowercaseVariableInFunction	Variable `...` in function should be lowercase
N807	DunderFunctionName	Function name should not start and end with `__`
N811	ConstantImportedAsNonConstant	Constant `...` imported as non-constant `...`
N812	LowercaseImportedAsNonLowercase	Lowercase `...` imported as non-lowercase `...`
N813	CamelcaseImportedAsLowercase	Camelcase `...` imported as lowercase `...`
N814	CamelcaseImportedAsConstant	Camelcase `...` imported as constant `...`
N815	MixedCaseVariableInClassScope	Variable `mixedCase` in class scope should not be mixedCase
N816	MixedCaseVariableInGlobalScope	Variable `mixedCase` in global scope should not be mixedCase
N817	CamelcaseImportedAsAcronym	Camelcase `...` imported as acronym `...`
N818	ErrorSuffixOnExceptionName	Exception name `...` should be named with an Error suffix

flake8-2020 (YTT)

For more, see flake8-2020 on PyPI.

Code	Name	Message
YTT101	SysVersionSlice3Referenced	`sys.version[:3]` referenced (python3.10), use `sys.version_info`
YTT102	SysVersion2Referenced	`sys.version[2]` referenced (python3.10), use `sys.version_info`
YTT103	SysVersionCmpStr3	`sys.version` compared to string (python3.10), use `sys.version_info`
YTT201	SysVersionInfo0Eq3Referenced	`sys.version_info[0] == 3` referenced (python4), use `>=`
YTT202	SixPY3Referenced	`six.PY3` referenced (python4), use `not six.PY2`
YTT203	SysVersionInfo1CmpInt	`sys.version_info[1]` compared to integer (python4), compare `sys.version_info` to tuple
YTT204	SysVersionInfoMinorCmpInt	`sys.version_info.minor` compared to integer (python4), compare `sys.version_info` to tuple
YTT301	SysVersion0Referenced	`sys.version[0]` referenced (python10), use `sys.version_info`
YTT302	SysVersionCmpStr10	`sys.version` compared to string (python10), use `sys.version_info`
YTT303	SysVersionSlice1Referenced	`sys.version[:1]` referenced (python10), use `sys.version_info`

flake8-annotations (ANN)

For more, see flake8-annotations on PyPI.

Code	Name	Message	Fix
ANN001	MissingTypeFunctionArgument	Missing type annotation for function argument `...`
ANN002	MissingTypeArgs	Missing type annotation for `*...`
ANN003	MissingTypeKwargs	Missing type annotation for `**...`
ANN101	MissingTypeSelf	Missing type annotation for `...` in method
ANN102	MissingTypeCls	Missing type annotation for `...` in classmethod
ANN201	MissingReturnTypePublicFunction	Missing return type annotation for public function `...`
ANN202	MissingReturnTypePrivateFunction	Missing return type annotation for private function `...`
ANN204	MissingReturnTypeSpecialMethod	Missing return type annotation for special method `...`	🛠
ANN205	MissingReturnTypeStaticMethod	Missing return type annotation for staticmethod `...`
ANN206	MissingReturnTypeClassMethod	Missing return type annotation for classmethod `...`
ANN401	DynamicallyTypedExpression	Dynamically typed expressions (typing.Any) are disallowed in `...`

flake8-bandit (S)

For more, see flake8-bandit on PyPI.

Code	Name	Message
S101	AssertUsed	Use of `assert` detected
S102	ExecUsed	Use of `exec` detected
S104	HardcodedBindAllInterfaces	Possible binding to all interfaces
S105	HardcodedPasswordString	Possible hardcoded password: `"..."`
S106	HardcodedPasswordFuncArg	Possible hardcoded password: `"..."`
S107	HardcodedPasswordDefault	Possible hardcoded password: `"..."`

flake8-blind-except (BLE)

For more, see flake8-blind-except on PyPI.

Code	Name	Message	Fix
BLE001	BlindExcept	Do not catch blind exception: `Exception`

flake8-boolean-trap (FBT)

For more, see flake8-boolean-trap on PyPI.

Code	Name	Message
FBT001	BooleanPositionalArgInFunctionDefinition	Boolean positional arg in function definition
FBT002	BooleanDefaultValueInFunctionDefinition	Boolean default value in function definition
FBT003	BooleanPositionalValueInFunctionCall	Boolean positional value in function call

flake8-bugbear (B)

For more, see flake8-bugbear on PyPI.

Code	Name	Message	Fix
B002	UnaryPrefixIncrement	Python does not support the unary prefix increment
B003	AssignmentToOsEnviron	Assigning to `os.environ` doesn't clear the environment
B004	UnreliableCallableCheck	Using `hasattr(x, '__call__')` to test if x is callable is unreliable. Use `callable(x)` for consistent results.
B005	StripWithMultiCharacters	Using `.strip()` with multi-character strings is misleading the reader
B006	MutableArgumentDefault	Do not use mutable data structures for argument defaults
B007	UnusedLoopControlVariable	Loop control variable `i` not used within the loop body	🛠
B008	FunctionCallArgumentDefault	Do not perform function call in argument defaults
B009	GetAttrWithConstant	Do not call `getattr` with a constant attribute value. It is not any safer than normal property access.	🛠
B010	SetAttrWithConstant	Do not call `setattr` with a constant attribute value. It is not any safer than normal property access.	🛠
B011	DoNotAssertFalse	Do not `assert False` (`python -O` removes these calls), raise `AssertionError()`	🛠
B012	JumpStatementInFinally	`return/continue/break` inside finally blocks cause exceptions to be silenced
B013	RedundantTupleInExceptionHandler	A length-one tuple literal is redundant. Write `except ValueError` instead of `except (ValueError,)`.	🛠
B014	DuplicateHandlerException	Exception handler with duplicate exception: `ValueError`	🛠
B015	UselessComparison	Pointless comparison. This comparison does nothing but waste CPU instructions. Either prepend `assert` or remove it.
B016	CannotRaiseLiteral	Cannot raise a literal. Did you intend to return it or raise an Exception?
B017	NoAssertRaisesException	`assertRaises(Exception)` should be considered evil
B018	UselessExpression	Found useless expression. Either assign it to a variable or remove it.
B019	CachedInstanceMethod	Use of `functools.lru_cache` or `functools.cache` on methods can lead to memory leaks
B020	LoopVariableOverridesIterator	Loop control variable `...` overrides iterable it iterates
B021	FStringDocstring	f-string used as docstring. This will be interpreted by python as a joined string rather than a docstring.
B022	UselessContextlibSuppress	No arguments passed to `contextlib.suppress`. No exceptions will be suppressed and therefore this context manager is redundant
B023	FunctionUsesLoopVariable	Function definition does not bind loop variable `...`
B024	AbstractBaseClassWithoutAbstractMethod	`...` is an abstract base class, but it has no abstract methods
B025	DuplicateTryBlockException	try-except block with duplicate exception `Exception`
B026	StarArgUnpackingAfterKeywordArg	Star-arg unpacking after a keyword argument is strongly discouraged
B027	EmptyMethodWithoutAbstractDecorator	`...` is an empty method in an abstract base class, but has no abstract decorator
B904	RaiseWithoutFromInsideExcept	Within an except clause, raise exceptions with raise ... from err or raise ... from None to distinguish them from errors in exception handling
B905	ZipWithoutExplicitStrict	`zip()` without an explicit `strict=` parameter

flake8-builtins (A)

For more, see flake8-builtins on PyPI.

Code	Name	Message
A001	BuiltinVariableShadowing	Variable `...` is shadowing a python builtin
A002	BuiltinArgumentShadowing	Argument `...` is shadowing a python builtin
A003	BuiltinAttributeShadowing	Class attribute `...` is shadowing a python builtin

flake8-comprehensions (C4)

For more, see flake8-comprehensions on PyPI.

Code	Name	Message	Fix
C400	UnnecessaryGeneratorList	Unnecessary generator (rewrite as a `list` comprehension)	🛠
C401	UnnecessaryGeneratorSet	Unnecessary generator (rewrite as a `set` comprehension)	🛠
C402	UnnecessaryGeneratorDict	Unnecessary generator (rewrite as a `dict` comprehension)	🛠
C403	UnnecessaryListComprehensionSet	Unnecessary `list` comprehension (rewrite as a `set` comprehension)	🛠
C404	UnnecessaryListComprehensionDict	Unnecessary `list` comprehension (rewrite as a `dict` comprehension)	🛠
C405	UnnecessaryLiteralSet	Unnecessary `(list\|tuple)` literal (rewrite as a `set` literal)	🛠
C406	UnnecessaryLiteralDict	Unnecessary `(list\|tuple)` literal (rewrite as a `dict` literal)	🛠
C408	UnnecessaryCollectionCall	Unnecessary `(dict\|list\|tuple)` call (rewrite as a literal)	🛠
C409	UnnecessaryLiteralWithinTupleCall	Unnecessary `(list\|tuple)` literal passed to `tuple()` (remove the outer call to `tuple()`)	🛠
C410	UnnecessaryLiteralWithinListCall	Unnecessary `(list\|tuple)` literal passed to `list()` (rewrite as a `list` literal)	🛠
C411	UnnecessaryListCall	Unnecessary `list` call (remove the outer call to `list()`)	🛠
C413	UnnecessaryCallAroundSorted	Unnecessary `(list\|reversed)` call around `sorted()`	🛠
C414	UnnecessaryDoubleCastOrProcess	Unnecessary `(list\|reversed\|set\|sorted\|tuple)` call within `(list\|set\|sorted\|tuple)()`
C415	UnnecessarySubscriptReversal	Unnecessary subscript reversal of iterable within `(reversed\|set\|sorted)()`
C416	UnnecessaryComprehension	Unnecessary `(list\|set)` comprehension (rewrite using `(list\|set)()`)	🛠
C417	UnnecessaryMap	Unnecessary `map` usage (rewrite using a `(list\|set\|dict)` comprehension)

flake8-debugger (T10)

For more, see flake8-debugger on PyPI.

Code	Name	Message	Fix
T100	Debugger	Import for `...` found

flake8-errmsg (EM)

For more, see flake8-errmsg on PyPI.

Code	Name	Message
EM101	RawStringInException	Exception must not use a string literal, assign to variable first
EM102	FStringInException	Exception must not use an f-string literal, assign to variable first
EM103	DotFormatInException	Exception must not use a `.format()` string directly, assign to variable first

flake8-implicit-str-concat (ISC)

For more, see flake8-implicit-str-concat on PyPI.

Code	Name	Message
ISC001	SingleLineImplicitStringConcatenation	Implicitly concatenated string literals on one line
ISC002	MultiLineImplicitStringConcatenation	Implicitly concatenated string literals over continuation line
ISC003	ExplicitStringConcatenation	Explicitly concatenated string should be implicitly concatenated

flake8-import-conventions (ICN)

Code	Name	Message	Fix
ICN001	ImportAliasIsNotConventional	`...` should be imported as `...`

flake8-print (T20)

For more, see flake8-print on PyPI.

Code	Name	Message	Fix
T201	PrintFound	`print` found	🛠
T203	PPrintFound	`pprint` found	🛠

flake8-pytest-style (PT)

For more, see flake8-pytest-style on PyPI.

Code	Name	Message	Fix
PT001	IncorrectFixtureParenthesesStyle	Use `@pytest.fixture()` over `@pytest.fixture`	🛠
PT002	FixturePositionalArgs	Configuration for fixture `...` specified via positional args, use kwargs
PT003	ExtraneousScopeFunction	`scope='function'` is implied in `@pytest.fixture()`
PT004	MissingFixtureNameUnderscore	Fixture `...` does not return anything, add leading underscore
PT005	IncorrectFixtureNameUnderscore	Fixture `...` returns a value, remove leading underscore
PT006	ParametrizeNamesWrongType	Wrong name(s) type in `@pytest.mark.parametrize`, expected `tuple`	🛠
PT007	ParametrizeValuesWrongType	Wrong values type in `@pytest.mark.parametrize` expected `list` of `tuple`
PT008	PatchWithLambda	Use `return_value=` instead of patching with lambda
PT009	UnittestAssertion	Use a regular assert instead of unittest-style '...'
PT010	RaisesWithoutException	set the expected exception in `pytest.raises()`
PT011	RaisesTooBroad	`pytest.raises(...)` is too broad, set the `match` parameter or use a more specific exception
PT012	RaisesWithMultipleStatements	`pytest.raises()` block should contain a single simple statement
PT013	IncorrectPytestImport	Found incorrect import of pytest, use simple `import pytest` instead
PT015	AssertAlwaysFalse	Assertion always fails, replace with `pytest.fail()`
PT016	FailWithoutMessage	No message passed to `pytest.fail()`
PT017	AssertInExcept	Found assertion on exception ... in except block, use pytest.raises() instead
PT018	CompositeAssertion	Assertion should be broken down into multiple parts
PT019	FixtureParamWithoutValue	Fixture ... without value is injected as parameter, use @pytest.mark.usefixtures instead
PT020	DeprecatedYieldFixture	`@pytest.yield_fixture` is deprecated, use `@pytest.fixture`
PT021	FixtureFinalizerCallback	Use `yield` instead of `request.addfinalizer`
PT022	UselessYieldFixture	No teardown in fixture ..., use `return` instead of `yield`
PT023	IncorrectMarkParenthesesStyle	Use `@pytest.mark....` over `@pytest.mark....()`	🛠
PT024	UnnecessaryAsyncioMarkOnFixture	`pytest.mark.asyncio` is unnecessary for fixtures
PT025	ErroneousUseFixturesOnFixture	`pytest.mark.usefixtures` has no effect on fixtures
PT026	UseFixturesWithoutParameters	Useless `pytest.mark.usefixtures` without parameters	🛠

flake8-quotes (Q)

For more, see flake8-quotes on PyPI.

Code	Name	Message
Q000	BadQuotesInlineString	Single quotes found but double quotes preferred
Q001	BadQuotesMultilineString	Single quote multiline found but double quotes preferred
Q002	BadQuotesDocstring	Single quote docstring found but double quotes preferred
Q003	AvoidQuoteEscape	Change outer quotes to avoid escaping inner quotes

flake8-return (RET)

For more, see flake8-return on PyPI.

Code	Name	Message	Fix
RET501	UnnecessaryReturnNone	Do not explicitly `return None` in function if it is the only possible return value	🛠
RET502	ImplicitReturnValue	Do not implicitly `return None` in function able to return non-`None` value	🛠
RET503	ImplicitReturn	Missing explicit `return` at the end of function able to return non-`None` value	🛠
RET504	UnnecessaryAssign	Unnecessary variable assignment before `return` statement
RET505	SuperfluousElseReturn	Unnecessary `else` after `return` statement
RET506	SuperfluousElseRaise	Unnecessary `else` after `raise` statement
RET507	SuperfluousElseContinue	Unnecessary `else` after `continue` statement
RET508	SuperfluousElseBreak	Unnecessary `else` after `break` statement

flake8-simplify (SIM)

For more, see flake8-simplify on PyPI.

Code	Name	Message	Fix
SIM118	KeyInDict	Use `key in dict` instead of `key in dict.keys()`	🛠
SIM222	OrTrue	Use `True` instead of `... or True`	🛠
SIM223	AndFalse	Use `False` instead of `... and False`	🛠
SIM300	YodaConditions	Use `left == right` instead of `right == left (Yoda-conditions)`

flake8-tidy-imports (TID)

For more, see flake8-tidy-imports on PyPI.

Code	Name	Message	Fix
TID251	BannedApi	`...` is banned: ...
TID252	BannedRelativeImport	Relative imports are banned

flake8-unused-arguments (ARG)

For more, see flake8-unused-arguments on PyPI.

Code	Name	Message
ARG001	UnusedFunctionArgument	Unused function argument: `...`
ARG002	UnusedMethodArgument	Unused method argument: `...`
ARG003	UnusedClassMethodArgument	Unused class method argument: `...`
ARG004	UnusedStaticMethodArgument	Unused static method argument: `...`
ARG005	UnusedLambdaArgument	Unused lambda argument: `...`

flake8-datetimez (DTZ)

For more, see flake8-datetimez on PyPI.

Code	Name	Message
DTZ001	CallDatetimeWithoutTzinfo	The use of `datetime.datetime()` without `tzinfo` argument is not allowed
DTZ002	CallDatetimeToday	The use of `datetime.datetime.today()` is not allowed
DTZ003	CallDatetimeUtcnow	The use of `datetime.datetime.utcnow()` is not allowed
DTZ004	CallDatetimeUtcfromtimestamp	The use of `datetime.datetime.utcfromtimestamp()` is not allowed
DTZ005	CallDatetimeNowWithoutTzinfo	The use of `datetime.datetime.now()` without `tz` argument is not allowed
DTZ006	CallDatetimeFromtimestamp	The use of `datetime.datetime.fromtimestamp()` without `tz` argument is not allowed
DTZ007	CallDatetimeStrptimeWithoutZone	The use of `datetime.datetime.strptime()` without %z must be followed by `.replace(tzinfo=)`
DTZ011	CallDateToday	The use of `datetime.date.today()` is not allowed.
DTZ012	CallDateFromtimestamp	The use of `datetime.date.fromtimestamp()` is not allowed

eradicate (ERA)

For more, see eradicate on PyPI.

Code	Name	Message	Fix
ERA001	CommentedOutCode	Found commented-out code	🛠

pandas-vet (PD)

For more, see pandas-vet on PyPI.

Code	Name	Message
PD002	UseOfInplaceArgument	`inplace=True` should be avoided; it has inconsistent behavior
PD003	UseOfDotIsNull	`.isna` is preferred to `.isnull`; functionality is equivalent
PD004	UseOfDotNotNull	`.notna` is preferred to `.notnull`; functionality is equivalent
PD007	UseOfDotIx	`.ix` is deprecated; use more explicit `.loc` or `.iloc`
PD008	UseOfDotAt	Use `.loc` instead of `.at`. If speed is important, use numpy.
PD009	UseOfDotIat	Use `.iloc` instead of `.iat`. If speed is important, use numpy.
PD010	UseOfDotPivotOrUnstack	`.pivot_table` is preferred to `.pivot` or `.unstack`; provides same functionality
PD011	UseOfDotValues	Use `.to_numpy()` instead of `.values`
PD012	UseOfDotReadTable	`.read_csv` is preferred to `.read_table`; provides same functionality
PD013	UseOfDotStack	`.melt` is preferred to `.stack`; provides same functionality
PD015	UseOfPdMerge	Use `.merge` method instead of `pd.merge` function. They have equivalent functionality.
PD901	DfIsABadVariableName	`df` is a bad variable name. Be kinder to your future self.

pygrep-hooks (PGH)

For more, see pygrep-hooks on GitHub.

Code	Name	Message
PGH001	NoEval	No builtin `eval()` allowed
PGH002	DeprecatedLogWarn	`warn` is deprecated in favor of `warning`
PGH003	BlanketTypeIgnore	Use specific error codes when ignoring type issues
PGH004	BlanketNOQA	Use specific error codes when using `noqa`

Pylint (PLC, PLE, PLR, PLW)

For more, see Pylint on PyPI.

Code	Name	Message	Fix
PLC0414	UselessImportAlias	Import alias does not rename original package	🛠
PLC2201	MisplacedComparisonConstant	Comparison should be ...	🛠
PLC3002	UnnecessaryDirectLambdaCall	Lambda expression called directly. Execute the expression inline instead.
PLE0117	NonlocalWithoutBinding	Nonlocal name `...` found without binding
PLE0118	UsedPriorGlobalDeclaration	Name `...` is used prior to global declaration on line 1
PLE1142	AwaitOutsideAsync	`await` should be used within an async function
PLR0206	PropertyWithParameters	Cannot have defined parameters for properties
PLR0402	ConsiderUsingFromImport	Use `from ... import ...` in lieu of alias
PLR1701	ConsiderMergingIsinstance	Merge these isinstance calls: `isinstance(..., (...))`
PLR1722	UseSysExit	Use `sys.exit()` instead of `exit`	🛠
PLW0120	UselessElseOnLoop	Else clause on loop without a break statement, remove the else and de-indent all the code inside it
PLW0602	GlobalVariableNotAssigned	Using global for `...` but no assignment is done

flake8-pie (PIE)

For more, see flake8-pie on PyPI.

Code	Name	Message	Fix
PIE790	NoUnnecessaryPass	Unnecessary `pass` statement	🛠
PIE794	DupeClassFieldDefinitions	Class field `...` is defined multiple times	🛠
PIE807	PreferListBuiltin	Prefer `list()` over useless lambda	🛠

Ruff-specific rules (RUF)

Code	Name	Message	Fix
RUF001	AmbiguousUnicodeCharacterString	String contains ambiguous unicode character '𝐁' (did you mean 'B'?)	🛠
RUF002	AmbiguousUnicodeCharacterDocstring	Docstring contains ambiguous unicode character '𝐁' (did you mean 'B'?)	🛠
RUF003	AmbiguousUnicodeCharacterComment	Comment contains ambiguous unicode character '𝐁' (did you mean 'B'?)	🛠
RUF004	KeywordArgumentBeforeStarArgument	Keyword argument `...` must come after starred arguments
RUF100	UnusedNOQA	Unused blanket `noqa` directive	🛠

Editor Integrations

VS Code (Official)

Download the Ruff VS Code extension, which supports autofix actions, import sorting, and more.

Language Server Protocol (Official)

Ruff supports the Language Server Protocol via the ruff-lsp Python package, available on PyPI.

ruff-lsp enables Ruff to be used with any editor that supports the Language Server Protocol, including Neovim, Sublime Text, Emacs, and more.

For example, to use ruff-lsp with Neovim, install ruff-lsp from PyPI along with nvim-lspconfig. Then, add something like the following to your init.lua:

-- See: https://github.com/neovim/nvim-lspconfig/tree/54eb2a070a4f389b1be0f98070f81d23e2b1a715#suggested-configuration
local opts = { noremap=true, silent=true }
vim.keymap.set('n', '<space>e', vim.diagnostic.open_float, opts)
vim.keymap.set('n', '[d', vim.diagnostic.goto_prev, opts)
vim.keymap.set('n', ']d', vim.diagnostic.goto_next, opts)
vim.keymap.set('n', '<space>q', vim.diagnostic.setloclist, opts)

-- Use an on_attach function to only map the following keys
-- after the language server attaches to the current buffer
local on_attach = function(client, bufnr)
  -- Enable completion triggered by <c-x><c-o>
  vim.api.nvim_buf_set_option(bufnr, 'omnifunc', 'v:lua.vim.lsp.omnifunc')

  -- Mappings.
  -- See `:help vim.lsp.*` for documentation on any of the below functions
  local bufopts = { noremap=true, silent=true, buffer=bufnr }
  vim.keymap.set('n', 'gD', vim.lsp.buf.declaration, bufopts)
  vim.keymap.set('n', 'gd', vim.lsp.buf.definition, bufopts)
  vim.keymap.set('n', 'K', vim.lsp.buf.hover, bufopts)
  vim.keymap.set('n', 'gi', vim.lsp.buf.implementation, bufopts)
  vim.keymap.set('n', '<C-k>', vim.lsp.buf.signature_help, bufopts)
  vim.keymap.set('n', '<space>wa', vim.lsp.buf.add_workspace_folder, bufopts)
  vim.keymap.set('n', '<space>wr', vim.lsp.buf.remove_workspace_folder, bufopts)
  vim.keymap.set('n', '<space>wl', function()
    print(vim.inspect(vim.lsp.buf.list_workspace_folders()))
  end, bufopts)
  vim.keymap.set('n', '<space>D', vim.lsp.buf.type_definition, bufopts)
  vim.keymap.set('n', '<space>rn', vim.lsp.buf.rename, bufopts)
  vim.keymap.set('n', '<space>ca', vim.lsp.buf.code_action, bufopts)
  vim.keymap.set('n', 'gr', vim.lsp.buf.references, bufopts)
  vim.keymap.set('n', '<space>f', function() vim.lsp.buf.format { async = true } end, bufopts)
end

-- Configure `ruff-lsp`.
local configs = require 'lspconfig.configs'
if not configs.ruff_lsp then
  configs.ruff_lsp = {
    default_config = {
      cmd = { 'ruff-lsp' },
      filetypes = { 'python' },
      root_dir = require('lspconfig').util.find_git_ancestor,
      init_options = {
        settings = {
          args = {}
        }
      }
    }
  }
end
require('lspconfig').ruff_lsp.setup {
  on_attach = on_attach,
}

Upon successful installation, you should see Ruff's diagnostics surfaced directly in your editor:

To use ruff-lsp with other editors, including Sublime Text and Helix, see the ruff-lsp documentation.

Language Server Protocol (Unofficial)

Ruff is also available as the python-lsp-ruff plugin for python-lsp-server, both of which are installable from PyPI:

pip install python-lsp-server python-lsp-ruff

The LSP server can then be used with any editor that supports the Language Server Protocol.

For example, to use python-lsp-ruff with Neovim, add something like the following to your init.lua:

require'lspconfig'.pylsp.setup {
  settings = {
    pylsp = {
      plugins = {
        ruff = {
          enabled = true
        },
        pycodestyle = {
          enabled = false
        },
        pyflakes = {
          enabled = false
        },
        mccabe = {
          enabled = false
        }
      }
    }
  },
}

Vim & Neovim

Ruff can be integrated into any editor that supports the Language Server Protocol via ruff-lsp (see: Language Server Protocol), including Vim and Neovim.

It's recommended that you use ruff-lsp, the officially supported LSP server for Ruff.

However, Ruff is also available as part of the coc-pyright extension for coc.nvim.

Ruff can also be integrated via efm in just a few lines.

tools:
  python-ruff: &python-ruff
    lint-command: 'ruff --config ~/myconfigs/linters/ruff.toml --quiet ${INPUT}'
    lint-stdin: true
    lint-formats:
      - '%f:%l:%c: %m'
    format-command: 'ruff --stdin-filename ${INPUT} --config ~/myconfigs/linters/ruff.toml --fix --exit-zero --quiet -'
    format-stdin: true

For neovim users using null-ls, Ruff is already integrated.

local null_ls = require("null-ls")
local methods = require("null-ls.methods")
local helpers = require("null-ls.helpers")

local function ruff_fix()
    return helpers.make_builtin({
        name = "ruff",
        meta = {
            url = "https://github.com/charliermarsh/ruff/",
            description = "An extremely fast Python linter, written in Rust.",
        },
        method = methods.internal.FORMATTING,
        filetypes = { "python" },
        generator_opts = {
            command = "ruff",
            args = { "--fix", "-e", "-n", "--stdin-filename", "$FILENAME", "-" },
            to_stdin = true
        },
        factory = helpers.formatter_factory
    })
end

null_ls.setup({
    sources = {
        ruff_fix(),
        null_ls.builtins.diagnostics.ruff,
    }
})

PyCharm (External Tool)

Ruff can be installed as an External Tool in PyCharm. Open the Preferences pane, then navigate to "Tools", then "External Tools". From there, add a new tool with the following configuration:

Ruff should then appear as a runnable action:

PyCharm (Unofficial)

Ruff is also available as the Ruff plugin on the IntelliJ Marketplace (maintained by @koxudaxi).

GitHub Actions

GitHub Actions has everything you need to run Ruff out-of-the-box:

name: CI
on: push
jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3
      - name: Install Python
        uses: actions/setup-python@v4
        with:
          python-version: "3.11"
      - name: Install dependencies
        run: |
          python -m pip install --upgrade pip
          pip install ruff
      - name: Run Ruff
        run: ruff .

FAQ

Is Ruff compatible with Black?

Yes. Ruff is compatible with Black out-of-the-box, as long as the line-length setting is consistent between the two.

As a project, Ruff is designed to be used alongside Black and, as such, will defer implementing stylistic lint rules that are obviated by autoformatting.

How does Ruff compare to Flake8?

(Coming from Flake8? Try flake8-to-ruff to automatically convert your existing configuration.)

Ruff can be used as a drop-in replacement for Flake8 when used (1) without or with a small number of plugins, (2) alongside Black, and (3) on Python 3 code.

Under those conditions, Ruff implements every rule in Flake8.

Ruff also re-implements some of the most popular Flake8 plugins and related code quality tools natively, including:

Note that, in some cases, Ruff uses different error code prefixes than would be found in the originating Flake8 plugins. For example, Ruff uses TID252 to represent the I252 rule from flake8-tidy-imports. This helps minimize conflicts across plugins and allows any individual plugin to be toggled on or off with a single (e.g.) --select TID, as opposed to --select I2 (to avoid conflicts with the isort rules, like I001).

Beyond the rule set, Ruff suffers from the following limitations vis-à-vis Flake8:

Ruff does not yet support structural pattern matching.
Flake8 has a plugin architecture and supports writing custom lint rules. (Instead, popular Flake8 plugins are re-implemented in Rust as part of Ruff itself.)

How does Ruff compare to Pylint?

At time of writing, Pylint implements 409 total rules, while Ruff implements 224, of which at least 60 overlap with the Pylint rule set. Subjectively, Pylint tends to implement more rules based on type inference (e.g., validating the number of arguments in a function call).

Like Flake8, Pylint supports plugins (called "checkers"), while Ruff implements all checks natively.

Unlike Pylint, Ruff is capable of automatically fixing its own lint errors.

Pylint parity is being tracked in #689.

Which tools does Ruff replace?

Today, Ruff can be used to replace Flake8 when used with any of the following plugins:

Ruff can also replace isort, yesqa, eradicate, pygrep-hooks (3/10), and a subset of the rules implemented in pyupgrade (21/33).

If you're looking to use Ruff, but rely on an unsupported Flake8 plugin, free to file an Issue.

Do I need to install Rust to use Ruff?

Nope! Ruff is available as ruff on PyPI:

pip install ruff

Ruff ships with wheels for all major platforms, which enables pip to install Ruff without relying on Rust at all.

Can I write my own plugins for Ruff?

Ruff does not yet support third-party plugins, though a plugin system is within-scope for the project. See #283 for more.

How does Ruff's import sorting compare to `isort`?

Ruff's import sorting is intended to be nearly equivalent to isort when used profile = "black". (There are some minor differences in how Ruff and isort break ties between similar imports.)

Like isort, Ruff's import sorting is compatible with Black.

Ruff is less configurable than isort, but supports the known-first-party, known-third-party, extra-standard-library, and src settings, like so:

[tool.ruff]
select = [
    # Pyflakes
    "F",
    # Pycodestyle
    "E",
    "W",
    # isort
    "I001"
]
src = ["src", "tests"]

[tool.ruff.isort]
known-first-party = ["my_module1", "my_module2"]

Does Ruff support Jupyter Notebooks?

Ruff is integrated into nbQA, a tool for running linters and code formatters over Jupyter Notebooks.

After installing ruff and nbqa, you can run Ruff over a notebook like so:

> nbqa ruff Untitled.ipynb
Untitled.ipynb:cell_1:2:5: F841 Local variable `x` is assigned to but never used
Untitled.ipynb:cell_2:1:1: E402 Module level import not at top of file
Untitled.ipynb:cell_2:1:8: F401 `os` imported but unused
Found 3 error(s).
1 potentially fixable with the --fix option.

Does Ruff support NumPy- or Google-style docstrings?

Yes! To enable specific docstring convention, add the following to your pyproject.toml:

[tool.ruff.pydocstyle]
convention = "google"  # Accepts: "google", "numpy", or "pep257".

For example, if you're coming from flake8-docstrings, and your originating configuration uses --docstring-convention=numpy, you'd instead set convention = "numpy" in your pyproject.toml, as above.

Note that setting a convention is equivalent to adding that convention's specific set of codes to your select. For example, convention = "numpy" is equivalent to:

[tool.ruff]
# Enable all `D` errors except `D107`, `D203`, `D212`, `D213`, `D402`, `D413`, `D415`, `D416`,
# and `D417`.
select = [
    "D100",
    "D101",
    "D102",
    "D103",
    "D104",
    "D105",
    "D106",
    "D200",
    "D201",
    "D202",
    "D204",
    "D205",
    "D206",
    "D207",
    "D208",
    "D209",
    "D210",
    "D211",
    "D214",
    "D215",
    "D300",
    "D301",
    "D400",
    "D403",
    "D404",
    "D405",
    "D406",
    "D407",
    "D408",
    "D409",
    "D410",
    "D411",
    "D412",
    "D414",
    "D418",
    "D419",
]

How can I tell what settings Ruff is using to check my code?

Run ruff /path/to/code.py --show-settings to view the resolved settings for a given file.

Development

Ruff is written in Rust (1.65.0). You'll need to install the Rust toolchain for development.

Assuming you have cargo installed, you can run:

cargo run resources/test/fixtures

For development, we use nightly Rust:

cargo +nightly fmt
cargo +nightly clippy --fix --workspace --all-targets --all-features -- -W clippy::pedantic
cargo +nightly test --all

Releases

Ruff is distributed on PyPI, and published via maturin.

See: .github/workflows/release.yaml.

Benchmarks

First, clone CPython. It's a large and diverse Python codebase, which makes it a good target for benchmarking.

git clone --branch 3.10 https://github.com/python/cpython.git resources/test/cpython

Add this pyproject.toml to the CPython directory:

[tool.ruff]
line-length = 88
extend-exclude = [
    "Lib/lib2to3/tests/data/bom.py",
    "Lib/lib2to3/tests/data/crlf.py",
    "Lib/lib2to3/tests/data/different_encoding.py",
    "Lib/lib2to3/tests/data/false_encoding.py",
    "Lib/lib2to3/tests/data/py2_test_grammar.py",
    "Lib/test/bad_coding2.py",
    "Lib/test/badsyntax_3131.py",
    "Lib/test/badsyntax_pep3120.py",
    "Lib/test/encoded_modules/module_iso_8859_1.py",
    "Lib/test/encoded_modules/module_koi8_r.py",
    "Lib/test/test_fstring.py",
    "Lib/test/test_grammar.py",
    "Lib/test/test_importlib/test_util.py",
    "Lib/test/test_named_expressions.py",
    "Lib/test/test_patma.py",
    "Lib/test/test_source_encoding.py",
    "Tools/c-analyzer/c_parser/parser/_delim.py",
    "Tools/i18n/pygettext.py",
    "Tools/test2to3/maintest.py",
    "Tools/test2to3/setup.py",
    "Tools/test2to3/test/test_foo.py",
    "Tools/test2to3/test2to3/hello.py",
]

Next, to benchmark the release build:

cargo build --release

hyperfine --ignore-failure --warmup 10 --runs 100 \
  "./target/release/ruff ./resources/test/cpython/ --no-cache" \
  "./target/release/ruff ./resources/test/cpython/"

Benchmark 1: ./target/release/ruff ./resources/test/cpython/ --no-cache
  Time (mean ± σ):     297.4 ms ±   4.9 ms    [User: 2460.0 ms, System: 67.2 ms]
  Range (min … max):   287.7 ms … 312.1 ms    100 runs

  Warning: Ignoring non-zero exit code.

Benchmark 2: ./target/release/ruff ./resources/test/cpython/
  Time (mean ± σ):      79.6 ms ±   7.3 ms    [User: 59.7 ms, System: 356.1 ms]
  Range (min … max):    62.4 ms … 111.2 ms    100 runs

  Warning: Ignoring non-zero exit code.

To benchmark against the ecosystem's existing tools:

hyperfine --ignore-failure --warmup 5 \
  "./target/release/ruff ./resources/test/cpython/ --no-cache" \
  "pylint --recursive=y resources/test/cpython/" \
  "pyflakes resources/test/cpython" \
  "autoflake --recursive --expand-star-imports --remove-all-unused-imports --remove-unused-variables --remove-duplicate-keys resources/test/cpython" \
  "pycodestyle resources/test/cpython" \
  "flake8 resources/test/cpython" \
  "python -m scripts.run_flake8 resources/test/cpython"

In order, these evaluate:

Ruff
Pylint
Pyflakes
autoflake
pycodestyle
Flake8
Flake8, with a hack to enable multiprocessing on macOS

(You can poetry install from ./scripts to create a working environment for the above.)

Benchmark 1: ./target/release/ruff ./resources/test/cpython/ --no-cache
  Time (mean ± σ):     297.9 ms ±   7.0 ms    [User: 2436.6 ms, System: 65.9 ms]
  Range (min … max):   289.9 ms … 314.6 ms    10 runs

  Warning: Ignoring non-zero exit code.

Benchmark 2: pylint --recursive=y resources/test/cpython/
  Time (mean ± σ):     37.634 s ±  0.225 s    [User: 36.728 s, System: 0.853 s]
  Range (min … max):   37.201 s … 38.106 s    10 runs

  Warning: Ignoring non-zero exit code.

Benchmark 3: pyflakes resources/test/cpython
  Time (mean ± σ):     40.950 s ±  0.449 s    [User: 40.688 s, System: 0.229 s]
  Range (min … max):   40.348 s … 41.671 s    10 runs

  Warning: Ignoring non-zero exit code.

Benchmark 4: autoflake --recursive --expand-star-imports --remove-all-unused-imports --remove-unused-variables --remove-duplicate-keys resources/test/cpython
  Time (mean ± σ):     11.562 s ±  0.160 s    [User: 107.022 s, System: 1.143 s]
  Range (min … max):   11.417 s … 11.917 s    10 runs

Benchmark 5: pycodestyle resources/test/cpython
  Time (mean ± σ):     67.428 s ±  0.985 s    [User: 67.199 s, System: 0.203 s]
  Range (min … max):   65.313 s … 68.496 s    10 runs

  Warning: Ignoring non-zero exit code.

Benchmark 6: flake8 resources/test/cpython
  Time (mean ± σ):     116.099 s ±  1.178 s    [User: 115.217 s, System: 0.845 s]
  Range (min … max):   114.180 s … 117.724 s    10 runs

  Warning: Ignoring non-zero exit code.

Benchmark 7: python -m scripts.run_flake8 resources/test/cpython
  Time (mean ± σ):     20.477 s ±  0.349 s    [User: 142.372 s, System: 1.504 s]
  Range (min … max):   20.107 s … 21.183 s    10 runs

Summary
  './target/release/ruff ./resources/test/cpython/ --no-cache' ran
   38.81 ± 1.05 times faster than 'autoflake --recursive --expand-star-imports --remove-all-unused-imports --remove-unused-variables --remove-duplicate-keys resources/test/cpython'
   68.74 ± 1.99 times faster than 'python -m scripts.run_flake8 resources/test/cpython'
  126.33 ± 3.05 times faster than 'pylint --recursive=y resources/test/cpython/'
  137.46 ± 3.55 times faster than 'pyflakes resources/test/cpython'
  226.35 ± 6.23 times faster than 'pycodestyle resources/test/cpython'
  389.73 ± 9.92 times faster than 'flake8 resources/test/cpython'

Reference

Options

`allowed-confusables`

A list of allowed "confusable" Unicode characters to ignore when enforcing RUF001, RUF002, and RUF003.

Default value: []

Type: Vec<char>

Example usage:

[tool.ruff]
# Allow minus-sign (U+2212), greek-small-letter-rho (U+03C1), and the asterisk-operator (U+2217),
# which could be confused for "-", "p", and "*", respectively.
allowed-confusables = ["−", "ρ", "∗"]

`cache-dir`

A path to the cache directory.

By default, Ruff stores cache results in a .ruff_cache directory in the current project root.

However, Ruff will also respect the RUFF_CACHE_DIR environment variable, which takes precedence over that default.

This setting will override even the RUFF_CACHE_DIR environment variable, if set.

Default value: .ruff_cache

Type: PathBuf

Example usage:

[tool.ruff]
cache-dir = "~/.cache/ruff"

`dummy-variable-rgx`

A regular expression used to identify "dummy" variables, or those which should be ignored when evaluating (e.g.) unused-variable checks. The default expression matches _, __, and _var, but not _var_.

Default value: "^(_+|(_+[a-zA-Z0-9_]*[a-zA-Z0-9]+?))$"

Type: Regex

Example usage:

[tool.ruff]
# Only ignore variables named "_".
dummy-variable-rgx = "^_$"

`exclude`

A list of file patterns to exclude from linting.

Exclusions are based on globs, and can be either:

Single-path patterns, like .mypy_cache (to exclude any directory named .mypy_cache in the tree), foo.py (to exclude any file named foo.py), or foo_*.py (to exclude any file matching foo_*.py ).
Relative patterns, like directory/foo.py (to exclude that specific file) or directory/*.py (to exclude any Python files in directory). Note that these paths are relative to the project root (e.g., the directory containing your pyproject.toml).

Note that you'll typically want to use extend-exclude to modify the excluded paths.

Default value: [".bzr", ".direnv", ".eggs", ".git", ".hg", ".mypy_cache", ".nox", ".pants.d", ".ruff_cache", ".svn", ".tox", ".venv", "__pypackages__", "_build", "buck-out", "build", "dist", "node_modules", "venv"]

Type: Vec<FilePattern>

Example usage:

[tool.ruff]
exclude = [".venv"]

`extend`

A path to a local pyproject.toml file to merge into this configuration. User home directory and environment variables will be expanded.

To resolve the current pyproject.toml file, Ruff will first resolve this base configuration file, then merge in any properties defined in the current configuration file.

Default value: None

Type: Path

Example usage:

[tool.ruff]
# Extend the `pyproject.toml` file in the parent directory.
extend = "../pyproject.toml"
# But use a different line length.
line-length = 100

`extend-exclude`

A list of file patterns to omit from linting, in addition to those specified by exclude.

Default value: []

Type: Vec<FilePattern>

Example usage:

[tool.ruff]
# In addition to the standard set of exclusions, omit all tests, plus a specific file.
extend-exclude = ["tests", "src/bad.py"]

`extend-ignore`

A list of check code prefixes to ignore, in addition to those specified by ignore.

Default value: []

Type: Vec<CheckCodePrefix>

Example usage:

[tool.ruff]
# Skip unused variable checks (`F841`).
extend-ignore = ["F841"]

`extend-select`

A list of check code prefixes to enable, in addition to those specified by select.

Default value: []

Type: Vec<CheckCodePrefix>

Example usage:

[tool.ruff]
# On top of the default `select` (`E`, `F`), enable flake8-bugbear (`B`) and flake8-quotes (`Q`).
extend-select = ["B", "Q"]

`external`

A list of check codes that are unsupported by Ruff, but should be preserved when (e.g.) validating # noqa directives. Useful for retaining # noqa directives that cover plugins not yet implemented in Ruff.

Default value: []

Type: Vec<String>

Example usage:

[tool.ruff]
# Avoiding flagging (and removing) `V101` from any `# noqa`
# directives, despite Ruff's lack of support for `vulture`.
external = ["V101"]

`fix`

Enable autofix behavior by-default when running ruff (overridden by the --fix and --no-fix command-line flags).

Default value: false

Type: bool

Example usage:

[tool.ruff]
fix = true

`fix-only`

Like fix, but disables reporting on leftover violation. Implies fix.

Default value: false

Type: bool

Example usage:

[tool.ruff]
fix-only = true

`fixable`

A list of check code prefixes to consider autofix-able.

Default value: ["A", "ANN", "ARG", "B", "BLE", "C", "D", "E", "ERA", "F", "FBT", "I", "ICN", "N", "PGH", "PLC", "PLE", "PLR", "PLW", "Q", "RET", "RUF", "S", "T", "TID", "UP", "W", "YTT"]

Type: Vec<CheckCodePrefix>

Example usage:

[tool.ruff]
# Only allow autofix behavior for `E` and `F` checks.
fixable = ["E", "F"]

`force-exclude`

Whether to enforce exclude and extend-exclude patterns, even for paths that are passed to Ruff explicitly. Typically, Ruff will lint any paths passed in directly, even if they would typically be excluded. Setting force-exclude = true will cause Ruff to respect these exclusions unequivocally.

This is useful for pre-commit, which explicitly passes all changed files to the ruff-pre-commit plugin, regardless of whether they're marked as excluded by Ruff's own settings.

Default value: false

Type: bool

Example usage:

[tool.ruff]
force-exclude = true

`format`

The style in which violation messages should be formatted: "text" (default), "grouped" (group messages by file), "json" (machine-readable), "junit" (machine-readable XML), "github" (GitHub Actions annotations) or "gitlab" (GitLab CI code quality report).

Default value: "text"

Type: SerializationType

Example usage:

[tool.ruff]
# Group violations by containing file.
format = "grouped"

`ignore`

A list of check code prefixes to ignore. Prefixes can specify exact checks (like F841), entire categories (like F), or anything in between.

When breaking ties between enabled and disabled checks (via select and ignore, respectively), more specific prefixes override less specific prefixes.

Default value: []

Type: Vec<CheckCodePrefix>

Example usage:

[tool.ruff]
# Skip unused variable checks (`F841`).
ignore = ["F841"]

`ignore-init-module-imports`

Avoid automatically removing unused imports in __init__.py files. Such imports will still be +flagged, but with a dedicated message suggesting that the import is either added to the module' +__all__ symbol, or re-exported with a redundant alias (e.g., import os as os).

Default value: false

Type: bool

Example usage:

[tool.ruff]
ignore-init-module-imports = true

`line-length`

The line length to use when enforcing long-lines violations (like E501).

Default value: 88

Type: usize

Example usage:

[tool.ruff]
# Allow lines to be as long as 120 characters.
line-length = 120

`per-file-ignores`

A list of mappings from file pattern to check code prefixes to exclude, when considering any matching files.

Default value: {}

Type: HashMap<String, Vec<CheckCodePrefix>>

Example usage:

[tool.ruff]
# Ignore `E402` (import violations) in all `__init__.py` files, and in `path/to/file.py`.
[tool.ruff.per-file-ignores]
"__init__.py" = ["E402"]
"path/to/file.py" = ["E402"]

`required-version`

Require a specific version of Ruff to be running (useful for unifying results across many environments, e.g., with a pyproject.toml file).

Default value: None

Type: String

Example usage:

[tool.ruff]
required-version = "0.0.193"

`respect-gitignore`

Whether to automatically exclude files that are ignored by .ignore, .gitignore, .git/info/exclude, and global gitignore files. Enabled by default.

Default value: true

Type: bool

Example usage:

[tool.ruff]
respect_gitignore = false

`select`

A list of check code prefixes to enable. Prefixes can specify exact checks (like F841), entire categories (like F), or anything in between.

When breaking ties between enabled and disabled checks (via select and ignore, respectively), more specific prefixes override less specific prefixes.

Default value: ["E", "F"]

Type: Vec<CheckCodePrefix>

Example usage:

[tool.ruff]
# On top of the defaults (`E`, `F`), enable flake8-bugbear (`B`) and flake8-quotes (`Q`).
select = ["E", "F", "B", "Q"]

`show-source`

Whether to show source code snippets when reporting lint error violations (overridden by the --show-source command-line flag).

Default value: false

Type: bool

Example usage:

[tool.ruff]
# By default, always show source code snippets.
show-source = true

`src`

The source code paths to consider, e.g., when resolving first- vs. third-party imports.

As an example: given a Python package structure like:

my_package/
  pyproject.toml
  src/
    my_package/
      __init__.py
      foo.py
      bar.py

The src directory should be included in source (e.g., source = ["src"]), such that when resolving imports, my_package.foo is considered a first-party import.

This field supports globs. For example, if you have a series of Python packages in a python_modules directory, src = ["python_modules/*"] would expand to incorporate all of the packages in that directory. User home directory and environment variables will also be expanded.

Default value: ["."]

Type: Vec<PathBuf>

Example usage:

[tool.ruff]
# Allow imports relative to the "src" and "test" directories.
src = ["src", "test"]

`target-version`

The Python version to target, e.g., when considering automatic code upgrades, like rewriting type annotations. Note that the target version will not be inferred from the current Python version, and instead must be specified explicitly (as seen below).

Default value: "py310"

Type: PythonVersion

Example usage:

[tool.ruff]
# Always generate Python 3.7-compatible code.
target-version = "py37"

`unfixable`

A list of check code prefixes to consider un-autofix-able.

Default value: []

Type: Vec<CheckCodePrefix>

Example usage:

[tool.ruff]
# Disable autofix for unused imports (`F401`).
unfixable = ["F401"]

`update-check`

Enable or disable automatic update checks (overridden by the --update-check and --no-update-check command-line flags).

Default value: true

Type: bool

Example usage:

[tool.ruff]
update-check = false

`flake8-annotations`

`allow-star-arg-any`

Whether to suppress ANN401 for dynamically typed *args and **kwargs arguments.

Default value: false

Type: bool

Example usage:

[tool.ruff.flake8-annotations]
allow-star-arg-any = true

`mypy-init-return`

Whether to allow the omission of a return type hint for __init__ if at least one argument is annotated.

Default value: false

Type: bool

Example usage:

[tool.ruff.flake8-annotations]
mypy-init-return = true

`suppress-dummy-args`

Whether to suppress ANN000-level errors for arguments matching the "dummy" variable regex (like _).

Default value: false

Type: bool

Example usage:

[tool.ruff.flake8-annotations]
suppress-dummy-args = true

`suppress-none-returning`

Whether to suppress ANN200-level errors for functions that meet either of the following criteria:

Contain no return statement.
Explicit return statement(s) all return None (explicitly or implicitly).

Default value: false

Type: bool

Example usage:

[tool.ruff.flake8-annotations]
suppress-none-returning = true

`flake8-bugbear`

`extend-immutable-calls`

Additional callable functions to consider "immutable" when evaluating, e.g., no-mutable-default-argument checks (B006).

Default value: []

Type: Vec<String>

Example usage:

[tool.ruff.flake8-bugbear]
# Allow default arguments like, e.g., `data: List[str] = fastapi.Query(None)`.
extend-immutable-calls = ["fastapi.Depends", "fastapi.Query"]

`flake8-errmsg`

`max-string-length`

Maximum string length for string literals in exception messages.

Default value: 0

Type: usize

Example usage:

[tool.ruff.flake8-errmsg]
max-string-length = 20

`flake8-import-conventions`

`aliases`

The conventional aliases for imports. These aliases can be extended by the extend_aliases option.

Default value: {"altair": "alt", "matplotlib.pyplot": "plt", "numpy": "np", "pandas": "pd", "seaborn": "sns"}

Type: FxHashMap<String, String>

Example usage:

[tool.ruff.flake8-import-conventions]
# Declare the default aliases.
altair = "alt"
matplotlib.pyplot = "plt"
numpy = "np"
pandas = "pd"
seaborn = "sns"

`extend-aliases`

A mapping of modules to their conventional import aliases. These aliases will be added to the aliases mapping.

Default value: {}

Type: FxHashMap<String, String>

Example usage:

[tool.ruff.flake8-import-conventions]
# Declare a custom alias for the `matplotlib` module.
"dask.dataframe" = "dd"

`flake8-pytest-style`

`fixture-parentheses`

Boolean flag specifying whether @pytest.fixture() without parameters should have parentheses. If the option is set to true (the default), @pytest.fixture() is valid and @pytest.fixture is an error. If set to false, @pytest.fixture is valid and @pytest.fixture() is an error.

Default value: true

Type: bool

Example usage:

[tool.ruff.flake8-pytest-style]
fixture-parentheses = true

`mark-parentheses`

Boolean flag specifying whether @pytest.mark.foo() without parameters should have parentheses. If the option is set to true (the default), @pytest.mark.foo() is valid and @pytest.mark.foo is an error. If set to false, @pytest.fixture is valid and @pytest.mark.foo() is an error.

Default value: true

Type: bool

Example usage:

[tool.ruff.flake8-pytest-style]
mark-parentheses = true

`parametrize-names-type`

Expected type for multiple argument names in @pytest.mark.parametrize. The following values are supported:

csv — a comma-separated list, e.g. @pytest.mark.parametrize('name1,name2', ...)
tuple (default) — e.g. @pytest.mark.parametrize(('name1', 'name2'), ...)
list — e.g. @pytest.mark.parametrize(['name1', 'name2'], ...)

Default value: tuple

Type: ParametrizeNameType

Example usage:

[tool.ruff.flake8-pytest-style]
parametrize-names-type = "list"

`parametrize-values-row-type`

Expected type for each row of values in @pytest.mark.parametrize in case of multiple parameters. The following values are supported:

tuple (default) — e.g. @pytest.mark.parametrize(('name1', 'name2'), [(1, 2), (3, 4)])
list — e.g. @pytest.mark.parametrize(('name1', 'name2'), [[1, 2], [3, 4]])

Default value: tuple

Type: ParametrizeValuesRowType

Example usage:

[tool.ruff.flake8-pytest-style]
parametrize-values-row-type = "list"

`parametrize-values-type`

Expected type for the list of values rows in @pytest.mark.parametrize. The following values are supported:

tuple — e.g. @pytest.mark.parametrize('name', (1, 2, 3))
list (default) — e.g. @pytest.mark.parametrize('name', [1, 2, 3])

Default value: list

Type: ParametrizeValuesType

Example usage:

[tool.ruff.flake8-pytest-style]
parametrize-values-type = "tuple"

`raises-extend-require-match-for`

List of additional exception names that require a match= parameter in a pytest.raises() call. This extends the default list of exceptions that require a match= parameter. This option is useful if you want to extend the default list of exceptions that require a match= parameter without having to specify the entire list. Note that this option does not remove any exceptions from the default list.

Default value: []

Type: Vec<String>

Example usage:

[tool.ruff.flake8-pytest-style]
raises-extend-require-match-for = ["requests.RequestException"]

`raises-require-match-for`

List of exception names that require a match= parameter in a pytest.raises() call.

Default value: ["BaseException", "Exception", "ValueError", "OSError", "IOError", "EnvironmentError", "socket.error"]

Type: Vec<String>

Example usage:

[tool.ruff.flake8-pytest-style]
raises-require-match-for = ["requests.RequestException"]

`flake8-quotes`

`avoid-escape`

Whether to avoid using single quotes if a string contains single quotes, or vice-versa with double quotes, as per PEP8. This minimizes the need to escape quotation marks within strings.

Default value: true

Type: bool

Example usage:

[tool.ruff.flake8-quotes]
# Don't bother trying to avoid escapes.
avoid-escape = false

`docstring-quotes`

Quote style to prefer for docstrings (either "single" (') or "double" (")).

Default value: "double"

Type: Quote

Example usage:

[tool.ruff.flake8-quotes]
docstring-quotes = "single"

`inline-quotes`

Quote style to prefer for inline strings (either "single" (') or "double" (")).

Default value: "double"

Type: Quote

Example usage:

[tool.ruff.flake8-quotes]
inline-quotes = "single"

`multiline-quotes`

Quote style to prefer for multiline strings (either "single" (') or "double" (")).

Default value: "double"

Type: Quote

Example usage:

[tool.ruff.flake8-quotes]
multiline-quotes = "single"

`flake8-tidy-imports`

`ban-relative-imports`

Whether to ban all relative imports ("all"), or only those imports that extend into the parent module or beyond ("parents").

Default value: "parents"

Type: Strictness

Example usage:

[tool.ruff.flake8-tidy-imports]
# Disallow all relative imports.
ban-relative-imports = "all"

`banned-api`

Specific modules or module members that may not be imported or accessed. Note that this check is only meant to flag accidental uses, and can be circumvented via eval or importlib.

Default value: {}

Type: HashMap<String, BannedApi>

Example usage:

[tool.ruff.flake8-tidy-imports]
[tool.ruff.flake8-tidy-imports.banned-api]
"cgi".msg = "The cgi module is deprecated, see https://peps.python.org/pep-0594/#cgi."
"typing.TypedDict".msg = "Use typing_extensions.TypedDict instead."

`flake8-unused-arguments`

`ignore-variadic-names`

Whether to allow unused variadic arguments, like *args and **kwargs.

Default value: false

Type: bool

Example usage:

[tool.ruff.flake8-unused-arguments]
ignore-variadic-names = true

`isort`

`combine-as-imports`

Combines as imports on the same line. See isort's combine-as-imports option.

Default value: false

Type: bool

Example usage:

[tool.ruff.isort]
combine-as-imports = true

`extra-standard-library`

A list of modules to consider standard-library, in addition to those known to Ruff in advance.

Default value: []

Type: Vec<String>

Example usage:

[tool.ruff.isort]
extra-standard-library = ["path"]

`force-single-line`

Forces all from imports to appear on their own line.

Default value: false

Type: bool

Example usage:

[tool.ruff.isort]
force-single-line = true

`force-wrap-aliases`

Force import from statements with multiple members and at least one alias (e.g., import A as B) to wrap such that every line contains exactly one member. For example, this formatting would be retained, rather than condensing to a single line:

from .utils import (
    test_directory as test_directory,
    test_id as test_id
)

Note that this setting is only effective when combined with combine-as-imports = true. When combine-as-imports isn't enabled, every aliased import from will be given its own line, in which case, wrapping is not necessary.

Default value: false

Type: bool

Example usage:

[tool.ruff.isort]
force-wrap-aliases = true
combine-as-imports = true

`known-first-party`

A list of modules to consider first-party, regardless of whether they can be identified as such via introspection of the local filesystem.

Default value: []

Type: Vec<String>

Example usage:

[tool.ruff.isort]
known-first-party = ["src"]

`known-third-party`

A list of modules to consider third-party, regardless of whether they can be identified as such via introspection of the local filesystem.

Default value: []

Type: Vec<String>

Example usage:

[tool.ruff.isort]
known-third-party = ["src"]

`single-line-exclusions`

One or more modules to exclude from the single line rule.

Default value: []

Type: Vec<String>

Example usage:

[tool.ruff.isort]
single-line-exclusions = ["os", "json"]

`split-on-trailing-comma`

If a comma is placed after the last member in a multi-line import, then the imports will never be folded into one line.

See isort's split-on-trailing-comma option.

Default value: true

Type: bool

Example usage:

[tool.ruff.isort]
split-on-trailing-comma = false

`mccabe`

`max-complexity`

The maximum McCabe complexity to allow before triggering C901 errors.

Default value: 10

Type: usize

Example usage:

[tool.ruff.mccabe]
# Flag errors (`C901`) whenever the complexity level exceeds 5.
max-complexity = 5

`pep8-naming`

`classmethod-decorators`

A list of decorators that, when applied to a method, indicate that the method should be treated as a class method. For example, Ruff will expect that any method decorated by a decorator in this list takes a cls argument as its first argument.

Default value: ["classmethod"]

Type: Vec<String>

Example usage:

[tool.ruff.pep8-naming]
# Allow Pydantic's `@validator` decorator to trigger class method treatment.
classmethod-decorators = ["classmethod", "pydantic.validator"]

`ignore-names`

A list of names to ignore when considering pep8-naming violations.

Default value: ["setUp", "tearDown", "setUpClass", "tearDownClass", "setUpModule", "tearDownModule", "asyncSetUp", "asyncTearDown", "setUpTestData", "failureException", "longMessage", "maxDiff"]

Type: Vec<String>

Example usage:

[tool.ruff.pep8-naming]
ignore-names = ["callMethod"]

`staticmethod-decorators`

A list of decorators that, when applied to a method, indicate that the method should be treated as a static method. For example, Ruff will expect that any method decorated by a decorator in this list has no self or cls argument.

Default value: ["staticmethod"]

Type: Vec<String>

Example usage:

[tool.ruff.pep8-naming]
# Allow a shorthand alias, `@stcmthd`, to trigger static method treatment.
staticmethod-decorators = ["staticmethod", "stcmthd"]

`pydocstyle`

`convention`

Whether to use Google-style or NumPy-style conventions or the PEP257 defaults when analyzing docstring sections.

Default value: None

Type: Convention

Example usage:

[tool.ruff.pydocstyle]
# Use Google-style docstrings.
convention = "google"

`pyupgrade`

`keep-runtime-typing`

Whether to avoid PEP 585 (List[int] -> list[int]) and PEP 604 (Optional[str] -> str | None) rewrites even if a file imports from __future__ import annotations. Note that this setting is only applicable when the target Python version is below 3.9 and 3.10 respectively.

Default value: false

Type: bool

Example usage:

[tool.ruff.pyupgrade]
# Preserve types, even if a file imports `from __future__ import annotations`.
keep-runtime-typing = true

License

MIT

Contributing

Contributions are welcome and hugely appreciated. To get started, check out the contributing guidelines.

Name		Name	Last commit message	Last commit date
Latest commit History 1,454 Commits
.cargo		.cargo
.github/workflows		.github/workflows
benches		benches
flake8_to_ruff		flake8_to_ruff
playground		playground
resources/test		resources/test
ruff		ruff
ruff_dev		ruff_dev
ruff_macros		ruff_macros
scripts		scripts
src		src
tests		tests
.editorconfig		.editorconfig
.gitignore		.gitignore
.pre-commit-config.yaml		.pre-commit-config.yaml
BREAKING_CHANGES.md		BREAKING_CHANGES.md
CODE_OF_CONDUCT.md		CODE_OF_CONDUCT.md
CONTRIBUTING.md		CONTRIBUTING.md
Cargo.lock		Cargo.lock
Cargo.toml		Cargo.toml
LICENSE		LICENSE
README.md		README.md
pyproject.toml		pyproject.toml
ruff.schema.json		ruff.schema.json
rust-toolchain		rust-toolchain
rustfmt.toml		rustfmt.toml
setup.py		setup.py

License

srini1971/ruff

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Ruff

Testimonials

Table of Contents

Installation and Usage

Installation

Usage

Configuration

pyproject.toml discovery

Python file discovery

Ignoring errors

"Action Comments"

Automating noqa Directives

Supported Rules

Pyflakes (F)

pycodestyle (E, W)

mccabe (C90)

isort (I)

pydocstyle (D)

pyupgrade (UP)

pep8-naming (N)

flake8-2020 (YTT)

flake8-annotations (ANN)

flake8-bandit (S)

flake8-blind-except (BLE)

flake8-boolean-trap (FBT)

flake8-bugbear (B)

flake8-builtins (A)

flake8-comprehensions (C4)

flake8-debugger (T10)

flake8-errmsg (EM)

flake8-implicit-str-concat (ISC)

flake8-import-conventions (ICN)

flake8-print (T20)

flake8-pytest-style (PT)

flake8-quotes (Q)

flake8-return (RET)

flake8-simplify (SIM)

flake8-tidy-imports (TID)

flake8-unused-arguments (ARG)

flake8-datetimez (DTZ)

eradicate (ERA)

pandas-vet (PD)

pygrep-hooks (PGH)

Pylint (PLC, PLE, PLR, PLW)

flake8-pie (PIE)

Ruff-specific rules (RUF)

Editor Integrations

VS Code (Official)

Language Server Protocol (Official)

Language Server Protocol (Unofficial)

Vim & Neovim

PyCharm (External Tool)

PyCharm (Unofficial)

GitHub Actions

FAQ

Is Ruff compatible with Black?

How does Ruff compare to Flake8?

How does Ruff compare to Pylint?

Which tools does Ruff replace?

Do I need to install Rust to use Ruff?

Can I write my own plugins for Ruff?

How does Ruff's import sorting compare to isort?

Does Ruff support Jupyter Notebooks?

Does Ruff support NumPy- or Google-style docstrings?

How can I tell what settings Ruff is using to check my code?

Development

Releases

Benchmarks

Reference

Options

flake8-annotations

flake8-bugbear

flake8-errmsg

flake8-import-conventions

`pyproject.toml` discovery

Automating `noqa` Directives

How does Ruff's import sorting compare to `isort`?

`flake8-annotations`

`flake8-bugbear`

`flake8-errmsg`

`flake8-import-conventions`

`flake8-pytest-style`

`flake8-quotes`

`flake8-tidy-imports`

`flake8-unused-arguments`

`isort`

`mccabe`

`pep8-naming`