head to head · open source
fastapi vs rswag
fastapi has 102,409 GitHub stars, 9,906 forks, 78 open issues and last shipped 5 days ago. rswag has 2,201 stars, 454 forks, 26 open issues and last shipped 26 days ago. fastapi leads on adoption by 4,553% (102,409 vs 2,201 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 | ★ 102K | ★ 2.2K |
| License | MIT | MIT |
| Written in | Python | Ruby |
| Last push | 2026-09-14 | 2026-08-24 |
| Forks | ⑂ 9.9K | ⑂ 454 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick fastapi if
- You weight community size — 102K 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 is an MIT licensed, high performance Python web framework for building APIs with standard Python type hints, aimed at Python developers and teams that need production ready HTTP services with automatic OpenAPI documentation.
read the full fastapi overview →
About rswag
rswag is an MIT licensed Ruby gem that extends rspec rails request specs with a Swagger based DSL, so a Rails API team can describe and test its endpoints in one place and generate OpenAPI 3.0 files plus an embedded swagger ui from green tests.
read the full rswag overview →
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Frequently asked questions
Is fastapi or rswag more popular?
fastapi has 102,409 GitHub stars and rswag has 2,201. 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 (102,409 stars) or its MIT licence terms. Choose rswag if its feature set, stack or MIT licence fits better. Both are self-hostable.