head to head · open source
fastapi vs rswag
fastapi has 104,566 GitHub stars, 10,179 forks, 78 open issues and last shipped yesterday. rswag has 2,203 stars, 454 forks, 26 open issues and last shipped 2 months ago. fastapi leads on adoption by 4,647% (104,566 vs 2,203 stars). fastapi is written in Python under MIT; rswag is written in Ruby under MIT. fastapi has attracted 10% as many forks as stars, rswag 21%. fastapi was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 1 topic tag (openapi), so they are genuine substitutes rather than adjacent tools.
Two open source projects, one decision. Both are free and self-hostable — the differences are community size, license terms, language stack and release pace.
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Side by side
| fastapi | rswag | |
|---|---|---|
| GitHub stars | ★ 105K | ★ 2.2K |
| License | MIT | MIT |
| Written in | Python | Ruby |
| Last push | 2026-11-02 | 2026-08-24 |
| Forks | ⑂ 10K | ⑂ 454 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick fastapi if
- You weight community size — 105K stars and counting
- You want the MIT license terms
- Your stack matches Python
- You value the larger contributor base for long-term maintenance
pick rswag if
- You want the rswag feature set and don't need the biggest community
- You prefer the MIT license terms
- Your stack matches Ruby
- You evaluated both and rswag fits your workflow better
About fastapi
FastAPI framework, high performance, easy to learn, fast to code, ready for production Documentation : Source Code : FastAPI is a modern, fast (high performance), web framework for building APIs with Python based on standard Python type hints. The key features are: Fast : Very high performance, on par with NodeJS and Go (thanks to Starlette and Pydantic). One of the fastest Python frameworks available. Fast to code : Increase the speed to develop features by about 200% to 300%. Fewer bugs : Reduce about 40% of human (developer) induced errors. Intuitive : Great editor support. Completion everywhere. Less time…
read the full fastapi overview →
About rswag
rswag ========= OpenApi 3.0 compatible! Seeking maintainers! Got a pet bug that needs fixing? Just let us know in your issue/pr that you'd like to step up to help. Rswag extends rspec rails "request specs" with a Swagger based DSL for describing and testing API operations. You describe your API operations with a succinct, intuitive syntax, and it automatically runs the tests. Once you have green tests, run a rake task to auto generate corresponding OpenAPI files and expose them as YAML or JSON endpoints. Rswag also provides an embedded version of the awesome swagger ui that's powered by the exposed file. This…
read the full rswag overview →
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Frequently asked questions
Is fastapi or rswag more popular?
fastapi has 104,566 GitHub stars and rswag has 2,203. fastapi has the larger community by that measure.
Are fastapi and rswag free?
Both are open source. fastapi is licensed under MIT and rswag under MIT. Neither carries a licence fee.
What is the difference between fastapi and rswag?
fastapi is written in Python and rswag in Ruby. The practical differences are community size, licence terms, language stack and release cadence — all compared in the table above.
Which should I choose, fastapi or rswag?
Choose fastapi if you want the larger community (104,566 stars) or its MIT licence terms. Choose rswag if its feature set, stack or MIT licence fits better. Both are self-hostable.