Give the agent you already use a memory you control. GBrain stores explicit facts with their sources, supports corrections and withdrawal, and makes the same memory available across your agents. Start with keyless memory and keyword retrieval; add semantic search, synthesis, and background enrichment when you need them.

GBrain is MIT-licensed and free to self-host; gbrain.io is optional paid hosting.

[!TIP] Need hosted? First time running an agent? Try gbrain.io, hosted GBrain, for the easiest experience: one brain for you and your team, connected to ChatGPT, Claude and Cursor, with nothing to install or keep online. Stuck? Email support@gbrain.io and a person will set it up with you, free.

Keep skills beside knowledge. New local brains include memory skills in their content root. Agents can join an authorized catalog; only approved editors can publish. Managed coding-agent installs add an owned native router; restart and real-use verification are separate steps. Staged migration preserves sharing choices and personal edits. See shared brain skills.

Choose your setup

1. Add GBrain to my existing agent — recommended. Keep your agent's identity and save memory inside its environment. No new personal-agent identity or private repository is required. Start with the guide for Grok Bot, Muse, or Codex / Claude Code. Other harnesses.
2. Use the brain on my own computer from everywhere. One command publishes it over MCP on your Tailscale tailnet and keeps it running: gbrain mcp expose (add --funnel for cloud agents such as Grok Bot, Muse and ChatGPT). Follow use your brain from anywhere over MCP. Say to your agent: "use my brain over mcp" — "put my brain on tailscale".
3. Connect my existing hosted brain. Follow hosted harness access to choose native OAuth or a private machine connection. For dashboard login, clients, and permissions, use MCP administration with the server's separate owner credential. Delegation is an explicit choice.

Grok Bot and Grok Build are different products. Muse's personal agent and Muse Code are different products too. Muse already has native editable memory; GBrain adds an explicit, portable record with provenance and shared access. See each guide's dated evidence and remaining verification steps.

I'm Garry Tan, President and CEO of Y Combinator. I built GBrain to run my own AI agents. It's the production brain behind my OpenClaw and Hermes deployments: 155,795 pages, 24,589 people, 5,340 companies, 66 cron jobs running autonomously. My agent ingests meetings, emails, tweets, voice calls, and original ideas while I sleep. It enriches every person and company it encounters. It fixes its own citations and consolidates memory overnight. I wake up smarter than when I went to bed — and so will you.

It works as a company brain too. Authenticated remote clients are constrained by source and operation grants plus visibility filters. Local files and shared database credentials are a different trust boundary: sources alone do not isolate those callers. The authorization tests exercise specific access paths, not a universal no-leak guarantee. Read the sharing boundaries and company-brain tutorial before setting up shared access.

Alongside keyword and semantic retrieval, GBrain offers two optional ways to use your stored knowledge:

• A synthesis layer that gives you the actual answer. Synthesized, well-cited prose across people, companies, deals, and ideas. Not "here are 10 chunks that mention your query"; an actual answer with citations and an explicit note on what the brain doesn't know yet. The gap analysis is the part that changes how you use the brain.
• A typed knowledge graph. Trusted local page writes extract supported references without LLM calls when auto-linking is enabled. Remote put_page edges arrive later, via sweeps, maintenance or add_link. Ask "who works at acme-example?": walks are breadth-first, milliseconds on dense clusters (how). On BrainBench relationship questions, relationship retrieval lifts production R@5 from 0.6626 to 0.7241 (benchmark); 0.9791 is the graph-oracle-parse upper bound, not a product score.

The point of building a 150K-page brain is to use it as a strategic moat. To never lose context. To query what's in your own head without re-reading it. The brain layer is what makes the moat usable. The 24/7 dream cycle is what keeps it sharp. Both run on your hardware, your DB, your keys.

It's easier to ship a daemon that runs 24/7 to ingest, enrich, and consolidate than it is to keep an agent in chat working hard. GBrain is that daemon, generalized. Install in 30 minutes. Your agent does the work. As my personal agent gets smarter, so does yours.

Start keyless. Your harness subscription and any separately configured model API usage are different costs. The optional personal-agent bootstrap takes about 15 minutes; always-on enrichment needs its own compute and API configuration.

Durable preferences and facts can be shared across agents; transient task and harness configuration state stay local. Configured cloud embedding, reranking, extraction, and synthesis providers can receive text, and the harness model sees recalled memory even in keyless mode. Markdown export is not a full database backup. Read memory boundaries.

LLMs: fetch llms.txt for the documentation map, or llms-full.txt for the same map with core docs inlined in one fetch. Agents: start with AGENTS.md (or CLAUDE.md if you're Claude Code).

What this looks like

Say you have a meeting with Alice tomorrow. You want to walk in remembering what she works on, when you last talked, and what's still open between you. Here's what you'd type, and what you'd get back.

You ask:

"What do I need to know before my meeting with Alice tomorrow?"

Most personal-knowledge tools give you back a list of pages. Something like:

1. people/alice — Alice runs engineering at Acme...
2. meetings/2026-03-15-alice-q1 — Q1 product review with Alice...
3. meetings/2026-01-08-acme-kickoff — Kickoff meeting with Acme team...
4. customers/acme — Acme is a series-B fintech we work with...
5. notes/2026-04-22 — Quick chat with Alice about pricing...

Five pages you now have to open and read yourself to actually prepare. The tool found the right material, but it didn't do the work.

GBrain gives you back the answer, with sources:

Alice runs engineering at Acme (a series-B fintech). You last spoke
on April 22 in a quick pricing chat. Three things are still open
from that conversation:

1. She owes you the security review for the new tier
   (deadline was May 1; no update since).
2. You committed to pricing for a 500-seat tier
   (you sent it April 25; no response yet).
3. She mentioned they're hiring a CISO; you said you'd intro
   someone from your network.

Heads up: nothing's been added to the brain about Alice or Acme
since April 22, six weeks ago. She may have replied through email
or Slack DM, channels the brain doesn't see. Worth asking her to
catch up before assuming any of this is still current.

Every claim has a source page behind it. The "heads up" at the end tells you what the brain doesn't know yet, so you can ask Alice about it directly instead of being surprised. The brain just did your meeting prep.

This is the difference between a search engine and a brain. Search finds the pages. The brain reads them for you and writes the answer.

Install

[!TIP] Fastest: hosted GBrain at gbrain.io, for any harness. One command launches a GBrain hosted on gbrain.io; Claude Code, Codex, ChatGPT, Cursor and every other AI you use connect to it, with nothing to keep online.

bash curl -sSL https://gbrainio.terminalwire.sh | bash gbrainio terminal connect # in a new terminal gbrainio workspace new # pick a plan in the browser claude mcp add --transport http --scope user gbrain https://gbrain.io/mcp codex mcp add gbrain --url https://gbrain.io/mcp

The installer is a shell script for macOS and Linux; read it before you run it.

Here's how to self-host it

GBrain is MIT-licensed and free to self-host. It needs Bun 1.4.4 or newer; existing worker installs read the authorization and queue upgrade guide before restarting on this version.

[!WARNING] GBrain is NOT distributed on npm. The npm gbrain package is unrelated and can shadow the real binary, so never run npm install -g gbrain or bun add -g gbrain. Install only via bun install -g github:garrytan/gbrain#latest-stable or git clone + bun install && bun link. Installed by mistake? gbrain doctor gives the fix. Schema not migrated (#218)? Run gbrain apply-migrations --yes --no-autopilot-install; if it exits 1, run gbrain doctor --json, not another --yes (wedged: relay its fix).

bun install -g github:garrytan/gbrain#latest-stable
gbrain setup claude-code              # or: gbrain setup codex
gbrain init --pglite --no-embedding   # any other harness, or no agent

gbrain setup shows wha