head to head · open source
langchain vs promptfoo
langchain has 146,538 GitHub stars, 24,504 forks, 492 open issues and last shipped yesterday. promptfoo has 25,231 stars, 2,331 forks, 651 open issues and last shipped yesterday. langchain leads on adoption by 481% (146,538 vs 25,231 stars). langchain is written in Python under MIT; promptfoo is written in TypeScript under MIT. langchain has attracted 17% as many forks as stars, promptfoo 9%. langchain 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
| langchain | promptfoo | |
|---|---|---|
| GitHub stars | ★ 147K | ★ 25K |
| License | MIT | MIT |
| Written in | Python | TypeScript |
| Last push | 2026-09-17 | 2026-09-17 |
| Forks | ⑂ 25K | ⑂ 2.3K |
| 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 promptfoo if
- You want the promptfoo feature set and don't need the biggest community
- You prefer the MIT license terms
- Your stack matches TypeScript
- You evaluated both and promptfoo 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 promptfoo
Promptfoo is an open source command line tool and TypeScript library for evaluating and red teaming large language model applications, aimed at developers, AI engineers, and security teams who need measurable evidence that a prompt, agent, or retrieval augmented generation pipeline behaves correctly and safely before it reaches users.
read the full promptfoo overview →
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Frequently asked questions
Is langchain or promptfoo more popular?
langchain has 146,538 GitHub stars and promptfoo has 25,231. langchain has the larger community by that measure.
Are langchain and promptfoo free?
Both are open source. langchain is licensed under MIT and promptfoo under MIT. Neither carries a licence fee.
What is the difference between langchain and promptfoo?
langchain is written in Python and promptfoo in TypeScript. 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 promptfoo?
Choose langchain if you want the larger community (146,538 stars) or its MIT licence terms. Choose promptfoo if its feature set, stack or MIT licence fits better. Both are self-hostable.