head to head · open source
OpenAPI-Specification vs fusio
OpenAPI-Specification has 31,225 GitHub stars, 9,155 forks, 80 open issues and last shipped 10 days ago. fusio has 2,116 stars, 241 forks, 169 open issues and last shipped 15 days ago. OpenAPI-Specification leads on adoption by 1,376% (31,225 vs 2,116 stars). OpenAPI-Specification is written in Markdown under Apache-2.0; fusio is written in PHP under Apache-2.0. OpenAPI-Specification has attracted 29% as many forks as stars, fusio 11%. OpenAPI-Specification 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
| OpenAPI-Specification | fusio | |
|---|---|---|
| GitHub stars | ★ 31K | ★ 2.1K |
| License | Apache-2.0 | Apache-2.0 |
| Written in | Markdown | PHP |
| Last push | 2026-09-11 | 2026-09-06 |
| Forks | ⑂ 9.2K | ⑂ 241 |
| 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 fusio if
- You want the fusio feature set and don't need the biggest community
- You prefer the Apache-2.0 license terms
- Your stack matches PHP
- You evaluated both and fusio 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 fusio
Fusio is a self hosted, open source API management platform and gateway written in PHP that turns internal business logic, legacy databases, and microservices into documented API products for third party developers and autonomous AI agents.
read the full fusio overview →
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Frequently asked questions
Is OpenAPI-Specification or fusio more popular?
OpenAPI-Specification has 31,225 GitHub stars and fusio has 2,116. OpenAPI-Specification has the larger community by that measure.
Are OpenAPI-Specification and fusio free?
Both are open source. OpenAPI-Specification is licensed under Apache-2.0 and fusio under Apache-2.0. Neither carries a licence fee.
What is the difference between OpenAPI-Specification and fusio?
OpenAPI-Specification is written in Markdown and fusio in PHP. 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 fusio?
Choose OpenAPI-Specification if you want the larger community (31,225 stars) or its Apache-2.0 licence terms. Choose fusio if its feature set, stack or Apache-2.0 licence fits better. Both are self-hostable.