head to head · open source
fastapi vs openapi-generator
fastapi has 104,542 GitHub stars, 10,173 forks, 78 open issues and last shipped 2 days ago. openapi-generator has 26,844 stars, 7,746 forks, 5,819 open issues and last shipped yesterday. fastapi leads on adoption by 289% (104,542 vs 26,844 stars). fastapi is written in Python under MIT; openapi-generator is written in Java under Apache-2.0. fastapi has attracted 10% as many forks as stars, openapi-generator 29%. openapi-generator was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 3 topic tags (api, openapi, openapi3), 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 | openapi-generator | |
|---|---|---|
| GitHub stars | ★ 105K | ★ 27K |
| License | MIT | Apache-2.0 |
| Written in | Python | Java |
| Last push | 2026-11-01 | 2026-11-02 |
| Forks | ⑂ 10K | ⑂ 7.7K |
| 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 openapi-generator if
- You want the openapi-generator feature set and don't need the biggest community
- You prefer the Apache-2.0 license terms
- Your stack matches Java
- You evaluated both and openapi-generator 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 openapi-generator
OpenAPI Generator Master ( 7.27.0 ): :star::star::star: If you would like to contribute, please refer to guidelines and a list of open tasks. :star::star::star: :bangbang: To migrate from Swagger Codegen to OpenAPI Generator, please refer to the migration guide :bangbang: :notebook with decorative cover: For more information, please refer to the Wiki page and FAQ :notebook with decorative cover: :notebook with decorative cover: The eBook A Beginner's Guide to Code Generation for REST APIs is a good starting point for beginners :notebook with decorative cover: :warning: If the OpenAPI spec, templates or any input…
read the full openapi-generator overview →
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Frequently asked questions
Is fastapi or openapi-generator more popular?
fastapi has 104,542 GitHub stars and openapi-generator has 26,844. fastapi has the larger community by that measure.
Are fastapi and openapi-generator free?
Both are open source. fastapi is licensed under MIT and openapi-generator under Apache-2.0. Neither carries a licence fee.
What is the difference between fastapi and openapi-generator?
fastapi is written in Python and openapi-generator in Java. 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 openapi-generator?
Choose fastapi if you want the larger community (104,542 stars) or its MIT licence terms. Choose openapi-generator if its feature set, stack or Apache-2.0 licence fits better. Both are self-hostable.