FastAPI vs Flask
Modern async-first APIs with typed validation versus the minimal, endlessly flexible classic microframework.
| Metric | fastapi/fastapi ★ 100k · MIT · Python | pallets/flask ★ 72k · BSD-3-Clause · Python |
|---|---|---|
| Trust score | 73 | 68 |
| Safety | 50 | 41 |
| Popularity | 100 | 97 |
| Maintenance | 100 | 100 |
| Lightweight | 50 | 50 |
By VOUCH's overall trust score, fastapi/fastapi edges ahead (73/100). Both are viable — pick based on the factors that matter to you.
FastAPI vs Flask: which should you choose?
FastAPI builds on type hints and Pydantic to give you automatic validation, async support, and OpenAPI docs out of the box, making it ideal for modern APIs. Flask is older and deliberately minimal, leaving most choices to you, which suits small apps and teams that want full control. Reach for FastAPI when you want speed and typed contracts; reach for Flask when you want simplicity and a huge body of existing extensions.
Scores above are computed live from fastapi/fastapi and pallets/flask using OSSF Scorecard, GitHub activity, popularity, and footprint signals.