head to head · open source
OpenAPI-Specification vs openapi-generator
OpenAPI-Specification has 31,215 GitHub stars, 9,156 forks, 80 open issues and last shipped 7 days ago. openapi-generator has 26,745 stars, 7,674 forks, 5,751 open issues and last shipped yesterday. OpenAPI-Specification leads on adoption by 17% (31,215 vs 26,745 stars). OpenAPI-Specification is written in Markdown under Apache-2.0; openapi-generator is written in Java under Apache-2.0. OpenAPI-Specification has attracted 29% 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 2 topic tags (openapi, rest), 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-Specification | openapi-generator | |
|---|---|---|
| GitHub stars | ★ 31K | ★ 27K |
| License | Apache-2.0 | Apache-2.0 |
| Written in | Markdown | Java |
| Last push | 2026-09-11 | 2026-09-17 |
| Forks | ⑂ 9.2K | ⑂ 7.7K |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick OpenAPI-Specification if
- You weight community size — 31K stars and counting
- You want the Apache-2.0 license terms
- Your stack matches Markdown
- 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 OpenAPI-Specification
The OpenAPI Specification (OAS) is a community driven open specification hosted within the OpenAPI Initiative, a Linux Foundation Collaborative Project. It defines a standard, programming language agnostic interface description for HTTP APIs, represented in YAML or JSON. The specification lives in the HTTP API tooling ecosystem, alongside the tools, libraries, and implementations listed in the repository's implementations document. The project source is released under the Apache 2.0 license, and its GitHub repository has accumulated roughly 31,000 stars and 9,100 forks across 13 years of activity.…
read the full OpenAPI-Specification 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 OpenAPI-Specification or openapi-generator more popular?
OpenAPI-Specification has 31,215 GitHub stars and openapi-generator has 26,745. OpenAPI-Specification has the larger community by that measure.
Are OpenAPI-Specification and openapi-generator free?
Both are open source. OpenAPI-Specification is licensed under Apache-2.0 and openapi-generator under Apache-2.0. Neither carries a licence fee.
What is the difference between OpenAPI-Specification and openapi-generator?
OpenAPI-Specification is written in Markdown 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, OpenAPI-Specification or openapi-generator?
Choose OpenAPI-Specification if you want the larger community (31,215 stars) or its Apache-2.0 licence terms. Choose openapi-generator if its feature set, stack or Apache-2.0 licence fits better. Both are self-hostable.