head to head · open source
OpenAPI-Specification vs fusio
OpenAPI-Specification has 31,295 GitHub stars, 9,144 forks, 80 open issues and last shipped 2 days ago. fusio has 2,129 stars, 247 forks, 169 open issues and last shipped 10 days ago. OpenAPI-Specification leads on adoption by 1,370% (31,295 vs 2,129 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 12%. 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 | 2026-11-03 | 2026-10-26 |
| Forks | ⑂ 9.1K | ⑂ 247 |
| 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 The OpenAPI Specification is a community driven open specification within the OpenAPI Initiative, a Linux Foundation Collaborative Project. The OpenAPI Specification (OAS) defines a standard, programming language agnostic interface description for HTTP APIs. This allows both humans and computers to discover and understand the capabilities of a service without requiring access to source code, additional documentation, or inspection of network traffic. When properly defined via OpenAPI, a consumer can understand and interact with the remote service with a minimal amount of implementation…
read the full OpenAPI-Specification overview →
About fusio
Fusio Open Source API Management Platform Turn your business logic into scalable API products for humans and AI agents. 📖 Documentation • 📺 Video Walkthrough (15m) • 💬 Discord Community Fusio is a self hosted, open source backend platform and API gateway written in PHP that bridges the gap between your internal infrastructure and the outside world. Whether you are exposing legacy databases, orchestrating microservices, or building custom business logic, Fusio handles the heavy lifting. It transforms your services into a professional API product, complete with an automated developer portal, SDK generation, and…
read the full fusio overview →
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Frequently asked questions
Is OpenAPI-Specification or fusio more popular?
OpenAPI-Specification has 31,295 GitHub stars and fusio has 2,129. 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 (31,295 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.