23 Openapi Docs

title: OpenAPI Documentation in FastAPI REST APIs weight: 33 date: 2026-06-28 lastmod: 2026-06-28 description: Customize FastAPI's automatic OpenAPI documentation including metadata, tags, descriptions, examples, security schemes, and custom Swagger UI configuration for better developer experience. tags: [api-development, fastapi]

FastAPI generates OpenAPI documentation automatically from route and model definitions, customizable with metadata tags, response examples, security scheme descriptions, and custom Swagger UI configuration.

```python
from fastapi import FastAPI, APIRouter
from fastapi.openapi.utils import get_openapi

app = FastAPI(
    title="E-Commerce API",
    description="REST API for e-commerce platform",
    version="2.0.0",
    contact={"name": "API Support", "email": "api@example.com"},
    license_info={"name": "MIT", "url": "https://opensource.org/licenses/MIT"},
    openapi_tags=[
        {"name": "Users", "description": "User management endpoints"},
        {"name": "Products", "description": "Product catalog operations"},
        {"name": "Orders", "description": "Order processing and tracking"}
    ]
)

def custom_openapi():
    if app.openapi_schema:
        return app.openapi_schema
    openapi_schema = get_openapi(
        title="E-Commerce API",
        version="2.0.0",
        description="Custom API description",
        routes=app.routes
    )
    openapi_schema["info"]["x-logo"] = {"url": "https://example.com/logo.png"}
    app.openapi_schema = openapi_schema
    return app.openapi_schema

app.openapi = custom_openapi

@router.get("/products", tags=["Products"])
async def list_products():
    """Get all products with pagination and filtering."""
    pass

What's Next

Now learn about security best practices in Building REST APIs with FastAPI.