diff --git a/app/domain/__init__.py b/app/domain/__init__.py
index b73080e7..908fbe13 100644
--- a/app/domain/__init__.py
+++ b/app/domain/__init__.py
@@ -1 +1,5 @@
 from domain.message import IrisMessage, IrisMessageRole
+from domain.course import Course
+from domain.exercise import ProgrammingExercise
+from domain.submission import ProgrammingSubmission
+from domain.codehint import CodeHint
diff --git a/app/domain/codehint.py b/app/domain/codehint.py
new file mode 100644
index 00000000..45a16d8a
--- /dev/null
+++ b/app/domain/codehint.py
@@ -0,0 +1,28 @@
+from pydantic import BaseModel
+
+
+class ProgrammingExerciseSolutionEntry(BaseModel):
+    file_path: str
+    previous_line: int
+    line: int
+    previous_code: str
+    code: str
+
+    def __str__(self):
+        return (
+            f'ProgrammingExerciseSolutionEntry(file_path="{self.file_path}", previous_line={self.previous_line}, '
+            f'line={self.line}, previous_code="{self.previous_code}", code="{self.code}")'
+        )
+
+
+class CodeHint(BaseModel):
+    title: str
+    description: str
+    content: str
+    solution_entries: [ProgrammingExerciseSolutionEntry]
+
+    def __str__(self):
+        return (
+            f'CodeHint(title="{self.title}", description="{self.description}", content="{self.content}", '
+            f"solution_entries={self.solution_entries})"
+        )
diff --git a/app/domain/course.py b/app/domain/course.py
new file mode 100644
index 00000000..c88511dc
--- /dev/null
+++ b/app/domain/course.py
@@ -0,0 +1,9 @@
+from pydantic import BaseModel
+
+
+class Course(BaseModel):
+    title: str
+    description: str
+
+    def __str__(self):
+        return f'Course(title="{self.title}", description="{self.description}")'
diff --git a/app/domain/dtos.py b/app/domain/dtos.py
new file mode 100644
index 00000000..eb723f8f
--- /dev/null
+++ b/app/domain/dtos.py
@@ -0,0 +1,60 @@
+from pydantic import BaseModel
+
+from domain import (
+    Course,
+    ProgrammingExercise,
+    IrisMessage,
+    ProgrammingSubmission,
+    CodeHint,
+)
+
+
+class ProgrammingExerciseTutorChatDTO(BaseModel):
+    course: Course
+    exercise: ProgrammingExercise
+    submission: ProgrammingSubmission
+    chat_history: [IrisMessage]
+
+    def __str__(self):
+        return (
+            f"ProgrammingExerciseTutorChatDTO(course={self.course}, exercise={self.exercise}, "
+            f"submission={self.submission}, chat_history={self.chat_history})"
+        )
+
+
+class CodeEditorChatDTO(BaseModel):
+    problem_statement: str
+    solution_repository: dict[str, str]
+    template_repository: dict[str, str]
+    test_repository: dict[str, str]
+    chat_history: [IrisMessage]
+
+    def __str__(self):
+        return (
+            f'CodeEditorChatDTO(problem_statement="{self.problem_statement}", '
+            f"solution_repository={self.solution_repository}, template_repository={self.template_repository}, "
+            f"test_repository={self.test_repository}, chat_history={self.chat_history})"
+        )
+
+
+class CodeEditorAdaptDTO(BaseModel):
+    problem_statement: str
+    solution_repository: dict[str, str]
+    template_repository: dict[str, str]
+    test_repository: dict[str, str]
+    instructions: str
+
+    def __str__(self):
+        return (
+            f'CodeEditorAdaptDTO(problem_statement="{self.problem_statement}", '
+            f"solution_repository={self.solution_repository}, template_repository={self.template_repository}, "
+            f'test_repository={self.test_repository}, instructions="{self.instructions}")'
+        )
+
+
+class HestiaDTO(BaseModel):
+    code_hint: CodeHint
+    exercise: ProgrammingExercise
+
+    def __str__(self):
+        return f"HestiaDTO(code_hint={self.code_hint}, exercise={self.exercise})"
diff --git a/app/domain/exercise.py b/app/domain/exercise.py
new file mode 100644
index 00000000..be195e2c
--- /dev/null
+++ b/app/domain/exercise.py
@@ -0,0 +1,9 @@
+from pydantic import BaseModel
+
+
+class ProgrammingExercise(BaseModel):
+    title: str
+    problem_statement: str
+
+    def __str__(self):
+        return f'ProgrammingExercise(title="{self.title}", problem_statement="{self.problem_statement}")'
diff --git a/app/domain/message.py b/app/domain/message.py
index b1f521cc..9867138e 100644
--- a/app/domain/message.py
+++ b/app/domain/message.py
@@ -1,5 +1,7 @@
 from enum import Enum
 
+from pydantic import BaseModel
+
 
 class IrisMessageRole(Enum):
     USER = "user"
@@ -7,13 +9,12 @@ class IrisMessageRole(Enum):
     SYSTEM = "system"
 
 
-class IrisMessage:
+class IrisMessage(BaseModel):
     role: IrisMessageRole
     text: str
 
     def __init__(self, role: IrisMessageRole, text: str):
-        self.role = role
-        self.text = text
+        super().__init__(role=role, text=text)
 
     def __str__(self):
         return f"IrisMessage(role={self.role.value}, text='{self.text}')"
diff --git a/app/domain/submission.py b/app/domain/submission.py
new file mode 100644
index 00000000..e64b8a4b
--- /dev/null
+++ b/app/domain/submission.py
@@ -0,0 +1,21 @@
+from pydantic import BaseModel
+
+
+class BuildLogEntry(BaseModel):
+    time: str
+    message: str
+
+    def __str__(self):
+        return f'BuildLogEntry(time="{self.time}", message="{self.message}")'
+
+
+class ProgrammingSubmission(BaseModel):
+    commit_hash: str
+    build_failed: bool
+    build_log_entries: [BuildLogEntry]
+
+    def __str__(self):
+        return (
+            f'ProgrammingSubmission(commit_hash="{self.commit_hash}", build_failed={self.build_failed}, '
+            f"build_log_entries={self.build_log_entries})"
+        )