head to head · open source
faiss vs Langfuse
faiss has 41,251 GitHub stars, 4,584 forks, 327 open issues and last shipped 2 days ago. Langfuse has 36,898 stars, 4,146 forks, 926 open issues and last shipped yesterday. faiss leads on adoption by 12% (41,251 vs 36,898 stars). faiss is written in C++ under MIT; Langfuse is written in TypeScript under a custom or non-standard licence. faiss has attracted 11% as many forks as stars, Langfuse 11%. Langfuse 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
| faiss | Langfuse | |
|---|---|---|
| GitHub stars | ★ 41K | ★ 37K |
| License | MIT | Custom / other |
| Written in | C++ | TypeScript |
| Last push | 2026-11-01 | 2026-11-02 |
| Forks | ⑂ 4.6K | ⑂ 4.1K |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick faiss if
- You weight community size — 41K stars and counting
- You want the MIT license terms
- Your stack matches C++
- You value the larger contributor base for long-term maintenance
pick Langfuse if
- You want the Langfuse feature set and don't need the biggest community
- You prefer the Custom / other license terms
- Your stack matches TypeScript
- You evaluated both and Langfuse fits your workflow better
About faiss
Faiss Faiss is a library for efficient similarity search and clustering of dense vectors. It contains algorithms that search in sets of vectors of any size, up to ones that possibly do not fit in RAM. It also contains supporting code for evaluation and parameter tuning. Faiss is written in C++ with complete wrappers for Python/numpy. Some of the most useful algorithms are implemented on the GPU. It is developed primarily at Meta's Fundamental AI Research group. News See CHANGELOG.md for detailed information about latest features. Introduction Faiss contains several methods for similarity search. It assumes that…
read the full faiss overview →
About Langfuse
Langfuse Cloud · Self Host · Demo Docs · Report Bug · Feature Request · Changelog · Roadmap · Langfuse is an open source LLM engineering platform. It helps teams collaboratively develop, monitor, evaluate, and debug AI applications. Langfuse can be self hosted in minutes and is battle tested . Proudly made with ClickHouse open source database. 🧑💻 We're hiring Langfuse is growing fast (we doubled the team in the last 6 months) since January 2026 we're part of ClickHouse, we're hiring engineering hybrid across the EU. We hire engineers who love open source and great developer experiences. See open roles → ✨…
read the full Langfuse overview →
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Frequently asked questions
Is faiss or Langfuse more popular?
faiss has 41,251 GitHub stars and Langfuse has 36,898. faiss has the larger community by that measure.
Are faiss and Langfuse free?
Both are open source. faiss is licensed under MIT, and Langfuse has no licence declared in this registry. Both are free to self-host.
What is the difference between faiss and Langfuse?
faiss is written in C++ and Langfuse 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, faiss or Langfuse?
Choose faiss if you want the larger community (41,251 stars) or its MIT licence terms. Choose Langfuse if its feature set, stack or Custom / other licence fits better. Both are self-hostable.