head to head · open source
llama_index vs faiss
llama_index has 52,206 GitHub stars, 8,165 forks, 770 open issues and last shipped yesterday. faiss has 40,929 stars, 4,526 forks, 327 open issues and last shipped yesterday. llama_index leads on adoption by 28% (52,206 vs 40,929 stars). llama_index is written in Python under MIT; faiss is written in C++ under MIT. llama_index has attracted 16% as many forks as stars, faiss 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.
← all 13541 open source comparisons
Side by side
| llama_index | faiss | |
|---|---|---|
| GitHub stars | ★ 52K | ★ 41K |
| License | MIT | MIT |
| Written in | Python | C++ |
| Last push | 2026-09-18 | 2026-09-18 |
| Forks | ⑂ 8.2K | ⑂ 4.5K |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick llama_index if
- You weight community size — 52K stars and counting
- You want the MIT license terms
- Your stack matches Python
- You value the larger contributor base for long-term maintenance
pick faiss if
- You want the faiss feature set and don't need the biggest community
- You prefer the MIT license terms
- Your stack matches C++
- You evaluated both and faiss fits your workflow better
About llama_index
LlamaIndex is an MIT licensed, open source Python framework for building agentic applications — retrieval augmented generation systems, agents and multi agent workflows — on top of private documents and data, and it is aimed at AI engineers and teams who need to connect large language models to their own sources of context.
read the full llama_index overview →
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 →
More in AI & Machine Learning
Related comparisons
More Machine Learning Infrastructure projects
Compare either of these against the rest of the Machine Learning Infrastructure field.
Frequently asked questions
Is llama_index or faiss more popular?
llama_index has 52,206 GitHub stars and faiss has 40,929. llama_index has the larger community by that measure.
Are llama_index and faiss free?
Both are open source. llama_index is licensed under MIT and faiss under MIT. Neither carries a licence fee.
What is the difference between llama_index and faiss?
llama_index is written in Python and faiss 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, llama_index or faiss?
Choose llama_index if you want the larger community (52,206 stars) or its MIT licence terms. Choose faiss if its feature set, stack or MIT licence fits better. Both are self-hostable.