head to head · open source
faiss vs Helicone
faiss has 40,939 GitHub stars, 4,527 forks, 327 open issues and last shipped yesterday. Helicone has 6,165 stars, 672 forks, 156 open issues and last shipped 4 days ago. faiss leads on adoption by 564% (40,939 vs 6,165 stars). faiss is written in C++ under MIT; Helicone is written in TypeScript under Apache-2.0. faiss has attracted 11% as many forks as stars, Helicone 11%. faiss 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 | Helicone | |
|---|---|---|
| GitHub stars | ★ 41K | ★ 6.2K |
| License | MIT | Apache-2.0 |
| Written in | C++ | TypeScript |
| Last push | 2026-09-19 | 2026-09-16 |
| Forks | ⑂ 4.5K | ⑂ 672 |
| 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 Helicone if
- You want the Helicone feature set and don't need the biggest community
- You prefer the Apache-2.0 license terms
- Your stack matches TypeScript
- You evaluated both and Helicone fits your workflow better
About faiss
Faiss is an MIT licensed C++ library for efficient similarity search and clustering of dense vectors, with complete Python and NumPy wrappers, developed primarily at Meta's Fundamental AI Research group, and it is intended for engineers and researchers who need nearest neighbour search over vector sets that range from small collections to sets that possibly do not fit in RAM.
read the full faiss overview →
About Helicone
Helicone is an open source AI gateway and LLM observability platform for AI engineers who need to monitor, evaluate, and experiment with applications built on large language models.
read the full Helicone overview →
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Frequently asked questions
Is faiss or Helicone more popular?
faiss has 40,939 GitHub stars and Helicone has 6,165. faiss has the larger community by that measure.
Are faiss and Helicone free?
Both are open source. faiss is licensed under MIT and Helicone under Apache-2.0. Neither carries a licence fee.
What is the difference between faiss and Helicone?
faiss is written in C++ and Helicone 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 Helicone?
Choose faiss if you want the larger community (40,939 stars) or its MIT licence terms. Choose Helicone if its feature set, stack or Apache-2.0 licence fits better. Both are self-hostable.