head to head · open source
fastapi vs openapi-generator
fastapi has 102,402 GitHub stars, 9,903 forks, 78 open issues and last shipped 4 days ago. openapi-generator has 26,745 stars, 7,674 forks, 5,751 open issues and last shipped yesterday. fastapi leads on adoption by 283% (102,402 vs 26,745 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 | ★ 102K | ★ 27K |
| License | MIT | Apache-2.0 |
| Written in | Python | Java |
| Last push | 2026-09-14 | 2026-09-17 |
| Forks | ⑂ 9.9K | ⑂ 7.7K |
| 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 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 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 openapi-generator
OpenAPI Generator is an Apache 2.0 licensed Java tool that generates API client libraries, server stubs, documentation, and configuration automatically from an OpenAPI Specification, and it is built for development teams that keep a machine readable API description and want generated code to stay in step with it.
read the full openapi-generator overview →
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Frequently asked questions
Is fastapi or openapi-generator more popular?
fastapi has 102,402 GitHub stars and openapi-generator has 26,745. 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 (102,402 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.