Automatic Documentation 📖

FastAPI automatically generates interactive API documentation from your code. No extra work needed!

Interactive Documentation

Visit `http://localhost:8000/docs` while your server is running.

You can:

• See all endpoints

• View request/response schemas

• Try endpoints directly

• See example requests/responses

Alternative Documentation

Visit `http://localhost:8000/redoc` for an alternative documentation view.

OpenAPI Schema

Visit `http://localhost:8000/openapi.json` to see the raw OpenAPI specification as JSON.

Customizing Documentation

Add descriptions to your endpoints:

@app.get("/items/{item_id}")
async def get_item(item_id: int):
    '''Get a specific item by ID.

    Args:
        item_id: The ID of the item to retrieve

    Returns:
        The item details
    '''
    return {"id": item_id}

Adding Examples

from pydantic import BaseModel

class Item(BaseModel):
    name: str
    price: float

    class Config:
        schema_extra = {
            "example": {
                "name": "Laptop",
                "price": 999.99
            }
        }

Customizing API Info

app = FastAPI(
    title="My API",
    description="This is my awesome API",
    version="1.0.0",
    docs_url="/api/docs",
    redoc_url="/api/redoc",
)

Endpoint Metadata

@app.post(
    "/items",
    summary="Create Item",
    description="Create a new item in the database",
    tags=["items"],
    status_code=201
)
async def create_item(item: Item):
    return item

🔑 Key Takeaways

• ✅ FastAPI auto-generates docs

• ✅ Visit /docs for interactive UI

• ✅ Visit /redoc for alternative view

• ✅ /openapi.json has OpenAPI spec

• ✅ Add docstrings for descriptions

• ✅ Use examples in models

• ✅ Tag endpoints for organization