head to head · open source
langchain vs Cairn
langchain has 146,562 GitHub stars, 24,508 forks, 492 open issues and last shipped yesterday. Cairn has 2,834 stars, 379 forks, 10 open issues and last shipped 12 days ago. langchain leads on adoption by 5,072% (146,562 vs 2,834 stars). langchain is written in Python under MIT; Cairn is written in Python under AGPL-3.0. langchain has attracted 17% as many forks as stars, Cairn 13%. langchain was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 1 topic tag (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.
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Side by side
| langchain | Cairn | |
|---|---|---|
| GitHub stars | ★ 147K | ★ 2.8K |
| License | MIT | AGPL-3.0 |
| Written in | Python | Python |
| Last push | 2026-09-18 | 2026-09-07 |
| Forks | ⑂ 25K | ⑂ 379 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick langchain if
- You weight community size — 147K stars and counting
- You want the MIT license terms
- Your stack matches Python
- You value the larger contributor base for long-term maintenance
pick Cairn if
- You want the Cairn feature set and don't need the biggest community
- You prefer the AGPL-3.0 license terms
- Your stack matches Python
- You evaluated both and Cairn fits your workflow better
About langchain
LangChain is an open source framework for building agents and LLM powered applications, written in Python and released under the MIT license. It lives in the AI and machine learning ecosystem, specifically among AI development platforms, and it works by chaining together interoperable components and third party integrations so that AI application development becomes simpler. The project describes itself as the agent engineering platform, and its abstractions are designed to keep applications working as the underlying technology evolves.
read the full langchain overview →
About Cairn
Cairn is a general purpose AI state space search engine, written in Python and licensed AGPL 3.0, that takes a known origin and a defined goal and searches for a path through an unknown problem space — validated first on autonomous penetration testing, and aimed at security teams, red teamers, CTF players and AI agent developers facing problems with a clear starting point, a clear success condition and an unknown route between them.
read the full Cairn overview →
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Frequently asked questions
Is langchain or Cairn more popular?
langchain has 146,562 GitHub stars and Cairn has 2,834. langchain has the larger community by that measure.
Are langchain and Cairn free?
Both are open source. langchain is licensed under MIT and Cairn under AGPL-3.0. Neither carries a licence fee.
What is the difference between langchain and Cairn?
langchain is written in Python and Cairn 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 Cairn?
Choose langchain if you want the larger community (146,562 stars) or its MIT licence terms. Choose Cairn if its feature set, stack or AGPL-3.0 licence fits better. Both are self-hostable.