metaBrain
A local document memory for AI agents
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What is metaBrain?
metaBrain is an open-source, local-first document memory system designed specifically for AI tools, coding agents, and the humans who work with them. It provides a durable, searchable local store where agents can save notes, source snippets, task context, metadata, tags, links, and version history. Instead of creating private file conventions for every task, agents get a stable local store with predictable paths, searchable content, and retained versions.
The tool ships as an mb CLI, an optional mbd local daemon, and an embeddable MetaBrainCore Swift library. Key features include workspace-local storage at .metabrain/store.leveldb, lexical search with tag/metadata/path filters, structured documents with metadata and references, versioned updates with snapshots, unified diff patching, daemon support for multiple concurrent databases, and BSD 3-Clause open-source licensing. It supports macOS, Linux, and Windows.
metaBrain is built for AI developers, coding agents, and teams building autonomous LLM agents that need persistent memory across sessions. It solves context sprawl by giving agents a shared memory layer they can actually use—retrieving context by words, paths, tags, or metadata instead of hunting through scratch files. Humans can also collaborate by reading, searching, and editing documents in the store.
metaBrain pricing
Pricing model: Freemium
Free and open-source under BSD 3-Clause license. No paid tiers or subscriptions. The tool is completely free to use, with source code hosted on GitHub. A Mac native GUI is in review process and expected soon in the App Store.
metaBrain pros
- Open-source with BSD 3-Clause license
- Local-first architecture keeps data on your machine
- Simple CLI with only 5 core commands
- Workspace-local store at .metabrain/store.leveldb
- Lexical search with tag, metadata, and path filters
- Structured documents with metadata and tags
- Versioned updates keep snapshots of changes
- Unified diff patching without rewriting documents
- Daemon mode supports multiple concurrent databases
- Embeddable MetaBrainCore Swift library
- Cross-platform: macOS, Linux, and Windows support
- Predictable paths for agent automation
- Humans and agents can collaborate on same store
- No setup ceremony required for discovery
- Designed for long-running agent workflows
metaBrain cons
- No cloud sync or distributed storage support
- Mac native GUI still in review process
- Primarily CLI-focused, less visual for beginners
- Limited to local machine storage only
- No built-in vector embedding support
- Swift library limits embedding to Apple ecosystems
- No authentication or access control features
- New project with smaller community than established tools
Frequently asked questions about metaBrain
What is metaBrain?
metaBrain is an open-source local document memory for AI agents and humans. It gives every agent one durable, searchable place for notes, source snippets, task context, metadata, tags, links, and version history, solving the problem of context sprawl when using agents.
How do I install metaBrain?
Install via Homebrew by running: brew tap OpenCow42/tap && brew install mb. This installs both the mb CLI and mbd local daemon. The tool supports macOS, Linux, and Windows.
How does metaBrain help AI agents?
Agents do not need a private file convention for every task. metaBrain gives them a stable local store with predictable paths, searchable content, tags, metadata, references, and retained versions. Agents can retrieve context quickly with search, allowing re-injection of specific knowledge during agentic work.
Can humans collaborate with agents on metaBrain?
Yes. Humans can collaborate too by reading, searching, and editing documents in the store. The CLI is designed to be easy for both agents and humans to use.
Does metaBrain keep version history?
Yes. Updates keep snapshots, and the patch command can apply unified diffs to stored document bodies while keeping old versions available. This allows patching without rewriting and maintains version history.
What is the mbd daemon?
mbd is the optional local daemon that can serve multiple local metaBrain databases through one daemon, so agents can work with separate stores concurrently. It installs alongside the mb CLI via Homebrew.
Is metaBrain open-source?
Yes. The project is BSD 3-Clause licensed, hosted on GitHub at github.com/OpenCow42/metaBrain, and built in the open for local-first agent work.
What platforms does metaBrain support?
metaBrain currently supports macOS, Linux, and Windows. A Mac native GUI is in the review process and expected to show up in the App Store soon.