FastAPI is a modern, high-performance Python web framework for building APIs, built on standard Python type hints. This is my fork of fastapi/fastapi, kept in my account for reference — it’s the framework I reach for when I need to stand up a fast, well-documented Python API.
The concepts
FastAPI’s defining idea is that your type hints do double duty: the same annotations that make your code readable also drive request validation, serialization, and automatic interactive API documentation. Under the hood it builds on Starlette for the web layer and Pydantic for data validation, which is where its performance — on par with NodeJS and Go — comes from. Because it’s fully based on open standards like OpenAPI and JSON Schema, you get Swagger UI and schema generation for free, plus strong editor autocompletion that cuts down on debugging.
How to use it
You define endpoints as plain Python functions with typed parameters and Pydantic models, and FastAPI handles parsing, validation, and docs. The result is production-ready code with far less boilerplate than traditional frameworks, and interactive documentation that stays in sync with the code automatically.
Running it
FastAPI is installed from PyPI with pip install fastapi and typically served with an ASGI server such as Uvicorn. See the excellent official documentation for tutorials and deployment guidance.
Language: Python
Source code: github.com/avnit/fastapi
Upstream: github.com/fastapi/fastapi