// rag · StarTrail-org/LEANN

LEANN

The smallest vector index in the world: private RAG over everything on your laptop with 97% less storage.

★ 13.0k stars⑂ 1.2k forksMITupdated 2026-09
▦ visual — this project's README ships no embeddable screenshot,
so here's a placeholder. The guide below is complete regardless.
// project facts

Project facts

LEANN is an open-source rag & knowledge project by StarTrail-org (StarTrail-org/LEANN on GitHub). It has 13,012 GitHub stars and 1,179 forks, is released under the MIT license, and was last updated on GitHub on 29 September 2026.

GitHub stars
13,012
Forks
1,179
License
MIT
Last updated on GitHub
29 September 2026
Listing
Full install guide
Official site
Official site
// how it works

How it works

  1. Choose what to RAG over

    Pick a source: documents, email, browser history, chat exports, a codebase, or live data from platforms such as Slack via MCP servers.

  2. Install LEANN

    Install uv if needed, clone the repo for the examples, and install the leann package from PyPI into a fresh virtual environment.

  3. Build your index

    Use the builder API or the leann build CLI to index your data - the graph index stays dramatically smaller than a conventional embedding store.

  4. Search and chat

    Query with LeannSearcher, chat with LeannChat using a local or API model, or plug LEANN into Claude Code as its semantic-search MCP service.

// features

Why people love it

97% storage savings

Graph-based selective recomputation with high-degree-preserving pruning avoids storing every embedding, while the project reports no accuracy loss versus heavyweight solutions.

RAG on everything

Ready-made support for files (PDF, TXT, Markdown), Apple Mail, browser history, WeChat and iMessage, ChatGPT and Claude conversations, codebases, and live data via MCP servers.

Completely private

Your data never leaves your laptop: no cloud, no OpenAI requirement - local Hugging Face or Ollama models cover embedding and generation.

Declarative Python API

Build, search and chat in a few lines with LeannBuilder, LeannSearcher and LeannChat, plus a full CLI for scripting.

MCP semantic search for coding agents

Acts as a drop-in semantic search MCP service for Claude Code; the project's ContextBench comparison reported 2.1x the initial relevant-code recall of BM25 on 30 SWE-Bench Pro tasks.

Portable knowledge bases

The tiny index makes it cheap to copy your entire personal knowledge base between devices or share it with others.

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// run it

Run it yourself

  1. Clone the repository

    Clone LEANN (the README clones the original yichuan-w repository into a folder named leann) to access all examples and apps.

    git clone https://github.com/StarTrail-org/LEANN.git
    cd LEANN
  2. Install from PyPI

    Create a uv virtual environment and install the leann package into it.

    uv venv
    uv pip install leann
  3. Build and search an index

    Follow the README quick start: build an index with LeannBuilder, then query it with LeannSearcher or chat with LeannChat.

    python demo.py  # adapt the README quick-start snippet - see README for the exact code
// use cases

What you can build

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// faq

Questions, answered

Who maintains LEANN?

LEANN is maintained by StarTrail-org and contributors; the underlying research paper (arXiv 2506.08276) received a best paper award at MLSys 2026, per the project.

Is LEANN free to use?

Yes. It is MIT-licensed and runs on your own machine with zero cloud costs.

Does it need a paid API key?

No: embedding and generation can run fully locally (Hugging Face models, Ollama, LM Studio and others). API providers such as OpenAI are optional and use your own key.

How does LEANN compare with FAISS, Chroma or Milvus?

Those store full embedding vectors for every chunk; LEANN recomputes embeddings on demand from a pruned graph, trading some compute for roughly 97% less storage at personal scale.

How do I get started?

Install uv, clone the repo, uv pip install leann, and run the quick-start snippet to build and search your first index.

// keep exploring

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// alternatives

Alternatives in RAG & Knowledge

The most-starred other RAG & Knowledge projects in the LibreAI catalogue — the realistic shortlist if LEANN is not the right fit.

Get LEANN

Free and open — grab the source, star the repo, and start creating.