head to head · open source
faiss vs zvec
faiss has 40,929 GitHub stars, 4,526 forks, 327 open issues and last shipped yesterday. zvec has 15,964 stars, 996 forks, 56 open issues and last shipped yesterday. faiss leads on adoption by 156% (40,929 vs 15,964 stars). faiss is written in C++ under MIT; zvec is written in C++ under Apache-2.0. faiss has attracted 11% as many forks as stars, zvec 6%. 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 | zvec | |
|---|---|---|
| GitHub stars | ★ 41K | ★ 16K |
| License | MIT | Apache-2.0 |
| Written in | C++ | C++ |
| Last push | 2026-09-18 | 2026-09-18 |
| Forks | ⑂ 4.5K | ⑂ 996 |
| 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 zvec if
- You want the zvec feature set and don't need the biggest community
- You prefer the Apache-2.0 license terms
- Your stack matches C++
- You evaluated both and zvec 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 zvec
Zvec is an open source, in process vector database written in C++ and licensed under Apache 2.0, built to embed directly into applications so that vector search, full text search, and hybrid retrieval run inside the developer's own process instead of behind a separate service.
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Frequently asked questions
Is faiss or zvec more popular?
faiss has 40,929 GitHub stars and zvec has 15,964. faiss has the larger community by that measure.
Are faiss and zvec free?
Both are open source. faiss is licensed under MIT and zvec under Apache-2.0. Neither carries a licence fee.
What is the difference between faiss and zvec?
faiss is written in C++ and zvec in C++. 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 zvec?
Choose faiss if you want the larger community (40,929 stars) or its MIT licence terms. Choose zvec if its feature set, stack or Apache-2.0 licence fits better. Both are self-hostable.