diff --git a/.spellcheck-en-custom.txt b/.spellcheck-en-custom.txt
index f14aa3a2..f2f6ea8f 100644
--- a/.spellcheck-en-custom.txt
+++ b/.spellcheck-en-custom.txt
@@ -4,8 +4,12 @@ Abhishek
 Akash
 AMDGPU
 Anil
+API
+API's
+api
 arge
 arXiv
+ascii
 backend
 backends
 benchmarking
@@ -42,6 +46,7 @@ eval
 Excalidraw
 exfiltrate
 exfiltrating
+extensibility
 Finetuning
 formedness
 GFX
@@ -134,7 +139,9 @@ Standup
 subcommand
 subcommands
 subdirectory
+submodule
 Sudalairaj
+sync'ed
 Taj
 tatsu
 TBD
@@ -151,6 +158,7 @@ UI
 ui
 unquantized
 USM
+utf
 UX
 venv
 Vishnoi
@@ -165,3 +173,4 @@ XT
 XTX
 Xu
 YAML
+yaml
\ No newline at end of file
diff --git a/README.md b/README.md
index 8f4da43f..3d762fbb 100644
--- a/README.md
+++ b/README.md
@@ -29,7 +29,7 @@ The rules for merging depend on the type of change in question and its scope of
 
 ## Formatting Guidelines
 
-Design documents should be placed in `docs/`.
+Design documents should be placed in [docs/](./docs).
 
 ### Text
 
@@ -43,3 +43,7 @@ easily updated in the future as needed. Some options include:
 * [Mermaid](https://github.com/mermaid-js/mermaid#readme)
 * [Excalidraw](https://excalidraw.com/)
 ** Be sure to leave "Embed Scene" turned on when exporting the PNG.
+
+### API Specifications
+
+API definitions use the [OpenAPI Specification](https://www.openapis.org/) (OAS) written in [YAML](https://yaml.org/).
diff --git a/docs/backend/api-definitions-guidelines.md b/docs/backend/api-definitions-guidelines.md
new file mode 100644
index 00000000..f083f81a
--- /dev/null
+++ b/docs/backend/api-definitions-guidelines.md
@@ -0,0 +1,57 @@
+# API Definitions Guidelines
+
+This document describes how service APIs will be managed for `InstructLab` and the sub-components of the `InstructLab` backend.
+
+## What parts of InstructLab need service APIs?
+
+There are two primary classes of service APIs needed to support InstructLab:
+
+* `Platform APIs`: These are APIs that are ignorant of `InstructLab` and provide generic AI platform capabilities (e.g., Fine Tuning, SDG, Eval)
+* `InstructLab APIs`: These are the APIs that reflect the user-facing functionality of `InstructLab` itself. They are aware of the end-to-end `InstructLab` workflow.
+
+The `InstructLab APIs` are essential for hosting `InstructLab` as a service in a repeatable way. The `Platform APIs` are critical for component reuse and extensibility (e.g., new SDG algorithms for new taxonomy data types), but they are not strictly required for hosting `InstructLab` as a service.
+
+## How will service APIs be defined?
+
+Service APIs will be defined using the [OpenAPI Specification (OAS)](https://www.openapis.org/) written in [YAML](https://yaml.org/).
+
+## Where will service API definitions live?
+
+Service API definitions will live in a new repository: `instructlab/openapi`. This repo will have two primary responsibilities:
+
+1. House the static service API definitions
+2. Build and publish any language-specific generated packages for consumption by service implementation projects (see below)
+
+## How will service implementations reference shared APIs?
+
+When a project chooses to implement one or more service APIs, there are two acceptable methods for doing so, listed in order of preference:
+
+1. Consume a supported language-specific package. The `openapi` repo will build/publish/tag consumable packages with generated code for supported languages based on standard package distribution channels for the given language. This is the preferred method of consumption as it avoids repository references and code duplication.
+2. For languages without a supported package, the `openapi` repo may be held as a [git submodule](https://www.git-scm.com/book/en/v2/Git-Tools-Submodules).
+
+## Style Guidelines
+
+* Use `kebab-case` for path elements
+  * All characters must be in the [ascii](https://www.ascii-code.com/) character set to avoid percent encoding in URIs
+  * All letters must be lowercase
+  * Words are separated by the `-` (dash) character
+* Use `snake_case` for properties
+  * All characters must be in the [utf-8](https://www.w3schools.com/charsets/ref_html_utf8.asp) character set for simple `json` encoding
+  * Words are separated by the `_` (underscore) character
+* Use `UpperCamelCase` for internal reusable schema names
+  * These are internal names, so the character set is not limited
+  * Words are capitalized and concatenated with no separator
+
+## API Layout
+
+* There will be two main portions of the APIs:
+  * `instructlab.yaml`: This defines the user-facing `InstructLab` REST API
+  * `platform.yaml`: This defines the platform-level APIs used by the `InstructLab` workflow.
+* Each platform `Capability` should own its own fully-functional sub-API file that can be used by individual capability service implementations
+* Any schema object that is reused between endpoints should be housed in a schema file under the central `common` directory.
+
+## Versioning and Stability
+
+**WARNING** At this stage in development, we make no guarantees about stability and support for APIs!
+
+**FUTURE**: Once stabilized, the APIs will follow an agreed-upon form of [semantic versioning](https://semver.org/) so that users can rely on the API's stability. The decision of how to version the API and at what granularity to do so is still under discussion.
\ No newline at end of file