head to head · open source
faiss vs cognee
faiss has 40,929 GitHub stars, 4,526 forks, 327 open issues and last shipped yesterday. cognee has 30,794 stars, 3,054 forks, 495 open issues and last shipped yesterday. faiss leads on adoption by 33% (40,929 vs 30,794 stars). faiss is written in C++ under MIT; cognee is written in Python under Apache-2.0. faiss has attracted 11% as many forks as stars, cognee 10%. 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 | cognee | |
|---|---|---|
| GitHub stars | ★ 41K | ★ 31K |
| License | MIT | Apache-2.0 |
| Written in | C++ | Python |
| Last push | 2026-09-18 | 2026-09-18 |
| Forks | ⑂ 4.5K | ⑂ 3.1K |
| 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 cognee if
- You want the cognee feature set and don't need the biggest community
- You prefer the Apache-2.0 license terms
- Your stack matches Python
- You evaluated both and cognee 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 cognee
Cognee is an open source AI memory platform for agents, released under the Apache 2.0 license and written in Python. It ingests data in any format and builds a self hosted knowledge graph that agents query to recall, connect, and act with full context across sessions. The project lives in the Python ecosystem, installs through standard package managers, and sits in the AI and machine learning infrastructure category alongside graph databases and context engineering tooling. A companion research paper, "Optimizing the Interface Between Knowledge Graphs and LLMs for Complex Reasoning" by Markovic et al., 2025, docu…
read the full cognee overview →
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Frequently asked questions
Is faiss or cognee more popular?
faiss has 40,929 GitHub stars and cognee has 30,794. faiss has the larger community by that measure.
Are faiss and cognee free?
Both are open source. faiss is licensed under MIT and cognee under Apache-2.0. Neither carries a licence fee.
What is the difference between faiss and cognee?
faiss is written in C++ and cognee in Python. 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 cognee?
Choose faiss if you want the larger community (40,929 stars) or its MIT licence terms. Choose cognee if its feature set, stack or Apache-2.0 licence fits better. Both are self-hostable.