FastAPI

FastAPI is a Python framework for building web APIs. It uses standard Python type hints to validate requests and generate interactive documentation.

You write normal Python functions and annotate their parameters with types. FastAPI reads those hints to check incoming data, convert values and reject bad requests with clear error messages. It also produces an OpenAPI schema, so you get interactive API docs without writing them by hand.

• Request checks driven by Python type hints
• Interactive API docs generated automatically
• Editor completion for parameters and data models
• Built on Starlette and Pydantic
• Follows the OpenAPI and JSON Schema standards

Python developers building backends for web apps, mobile apps or machine learning services. It suits teams that want clear API contracts and fewer manual checks in their code.

FastAPI is free and open source under the MIT license. It runs under an ASGI server such as Uvicorn, so you need to install a server to run your app. The project also offers an optional cloud service for deployment, which is separate from the framework.