head to head · open source
langchain vs outlines
langchain has 148,892 GitHub stars, 25,031 forks, 492 open issues and last shipped yesterday. outlines has 15,998 stars, 911 forks, 166 open issues and last shipped 1 months ago. langchain leads on adoption by 831% (148,892 vs 15,998 stars). langchain is written in Python under MIT; outlines is written in Python under Apache-2.0. langchain has attracted 17% as many forks as stars, outlines 6%. langchain was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 1 topic tag (generative-ai), 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.
← all 20902 open source comparisons
Side by side
| langchain | outlines | |
|---|---|---|
| GitHub stars | ★ 149K | ★ 16K |
| License | MIT | Apache-2.0 |
| Written in | Python | Python |
| Last push | 2026-11-02 | 2026-09-21 |
| Forks | ⑂ 25K | ⑂ 911 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick langchain if
- You weight community size — 149K stars and counting
- You want the MIT license terms
- Your stack matches Python
- You value the larger contributor base for long-term maintenance
pick outlines if
- You want the outlines 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 outlines fits your workflow better
About langchain
The agent engineering platform. LangChain is a framework for building agents and LLM powered applications. It helps you chain together interoperable components and third party integrations to simplify AI application development — all while future proofing decisions as the underlying technology evolves. [!TIP] Just getting started? Check out Deep Agents — a higher level package built on LangChain for agents that have built in capabilities for common usage patterns such as planning, subagents, file system usage, and more. Quickstart If you're looking for more advanced customization or agent orchestration, check…
read the full langchain overview →
About outlines
🗒️ Structured outputs for LLMs 🗒️ Made with ❤👷️ by the team at .txt Trusted by NVIDIA, Cohere, HuggingFace, vLLM, etc. [![PyPI Version][pypi version badge]][pypi] [![Downloads][downloads badge]][pypistats] [![Stars][stars badge]][stars] [![Discord][discord badge]][discord] [![Blog][dottxt blog badge]][dottxt blog] [![Twitter][twitter badge]][twitter] The .txt API is currently in early access. Request access here → 🚀 Building the future of structured generation We're working with select partners to develop new interfaces to structured generation. Need XML, FHIR, custom schemas or grammars? Let's talk. Audit…
read the full outlines overview →
More in AI & Machine Learning
Related comparisons
More AI Development Platforms projects
Compare either of these against the rest of the AI Development Platforms field.
Frequently asked questions
Is langchain or outlines more popular?
langchain has 148,892 GitHub stars and outlines has 15,998. langchain has the larger community by that measure.
Are langchain and outlines free?
Both are open source. langchain is licensed under MIT and outlines under Apache-2.0. Neither carries a licence fee.
What is the difference between langchain and outlines?
langchain is written in Python and outlines 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, langchain or outlines?
Choose langchain if you want the larger community (148,892 stars) or its MIT licence terms. Choose outlines if its feature set, stack or Apache-2.0 licence fits better. Both are self-hostable.