head to head · open source
openapi-generator vs hey-api
openapi-generator has 26,846 GitHub stars, 7,748 forks, 5,819 open issues and last shipped yesterday. hey-api has 5,551 stars, 453 forks, 630 open issues and last shipped 3 days ago. openapi-generator leads on adoption by 384% (26,846 vs 5,551 stars). openapi-generator is written in Java under Apache-2.0; hey-api is written in TypeScript under MIT. openapi-generator has attracted 29% as many forks as stars, hey-api 8%. openapi-generator was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 2 topic tags (api-client, 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
| openapi-generator | hey-api | |
|---|---|---|
| GitHub stars | ★ 27K | ★ 5.6K |
| License | Apache-2.0 | MIT |
| Written in | Java | TypeScript |
| Last push | 2026-11-02 | 2026-10-31 |
| Forks | ⑂ 7.7K | ⑂ 453 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick openapi-generator if
- You weight community size — 27K stars and counting
- You want the Apache-2.0 license terms
- Your stack matches Java
- You value the larger contributor base for long-term maintenance
pick hey-api if
- You want the hey-api feature set and don't need the biggest community
- You prefer the MIT license terms
- Your stack matches TypeScript
- You evaluated both and hey-api fits your workflow better
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 →
About hey-api
Hey API "OpenAPI codegen that just works." — Guillermo Rauch, CEO of Vercel Manual • Issues • Contribute About Hey API is an ecosystem for turning API specifications into production ready code. It's trusted by thousands of companies – from YC startups to Fortune 500 enterprises – and powers products used by millions worldwide. This is the monorepo containing all open source Hey API packages. For package specific documentation and quick start guides, see the individual repositories below. Packages Package Description openapi ts TypeScript code generator with 20+ plugins for SDKs, Zod schemas, TanStack Query…
read the full hey-api overview →
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Frequently asked questions
Is openapi-generator or hey-api more popular?
openapi-generator has 26,846 GitHub stars and hey-api has 5,551. openapi-generator has the larger community by that measure.
Are openapi-generator and hey-api free?
Both are open source. openapi-generator is licensed under Apache-2.0 and hey-api under MIT. Neither carries a licence fee.
What is the difference between openapi-generator and hey-api?
openapi-generator is written in Java and hey-api in TypeScript. The practical differences are community size, licence terms, language stack and release cadence — all compared in the table above.
Which should I choose, openapi-generator or hey-api?
Choose openapi-generator if you want the larger community (26,846 stars) or its Apache-2.0 licence terms. Choose hey-api if its feature set, stack or MIT licence fits better. Both are self-hostable.