head to head · open source
OpenAPI-Specification vs optillm
OpenAPI-Specification has 31,225 GitHub stars, 9,155 forks, 80 open issues and last shipped 10 days ago. optillm has 4,296 stars, 388 forks, 23 open issues and last shipped 4 days ago. OpenAPI-Specification leads on adoption by 627% (31,225 vs 4,296 stars). OpenAPI-Specification is written in Markdown under Apache-2.0; optillm is written in Python under Apache-2.0. OpenAPI-Specification has attracted 29% as many forks as stars, optillm 9%. optillm was the more recently maintained of the two, and both are self-hostable with no licence fee.
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 | optillm | |
|---|---|---|
| GitHub stars | ★ 31K | ★ 4.3K |
| License | Apache-2.0 | Apache-2.0 |
| Written in | Markdown | Python |
| Last push | 2026-09-11 | 2026-09-17 |
| Forks | ⑂ 9.2K | ⑂ 388 |
| 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 optillm if
- You want the optillm feature set and don't need the biggest community
- You prefer the Apache-2.0 license terms
- Your stack matches Python
- You evaluated both and optillm 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 optillm
OptiLLM is a Python project that provides an optimizing inference proxy for large language models. It exposes an OpenAI API compatible endpoint and sits between an application and model providers, allowing callers to request reasoning oriented optimizations without changing model weights or adding training. The project lives in the developer tools and API development ecosystem, and its topics connect it to agents, agentic workflows, API gateways, chain of thought prompting, and generative AI inference.
read the full optillm overview →
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Frequently asked questions
Is OpenAPI-Specification or optillm more popular?
OpenAPI-Specification has 31,225 GitHub stars and optillm has 4,296. OpenAPI-Specification has the larger community by that measure.
Are OpenAPI-Specification and optillm free?
Both are open source. OpenAPI-Specification is licensed under Apache-2.0 and optillm under Apache-2.0. Neither carries a licence fee.
What is the difference between OpenAPI-Specification and optillm?
OpenAPI-Specification is written in Markdown and optillm in Python. 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 optillm?
Choose OpenAPI-Specification if you want the larger community (31,225 stars) or its Apache-2.0 licence terms. Choose optillm if its feature set, stack or Apache-2.0 licence fits better. Both are self-hostable.