gbrain

GBrain

Search gives you raw pages. GBrain gives you the answer. It's the brain layer your AI agent has been missing — the only one that does synthesis, graph traversal, and gap analysis in one box. Run a full autonomous agent on top of it, or just wire it into Claude Code or Codex as a supercharged retrieval layer in one command; either way your coding agent stops being amnesiac about everything that isn't code.

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. Each person on the team gets their own slice of the brain, scoped by login. When you query, you only see what you're allowed to see — never another person's notes, never another team's data. We fuzz-tested this across every way you can read the brain (search, list, lookup, multi-source reads) and got zero leaks. Drop GBrain in as your team's shared institutional memory — the company-brain shape on YC's Request for Startups. If you're building in that space, you might as well build on this. Tutorial: set up GBrain as your company brain →

Lots of personal-knowledge systems give you keyword matching and grep in a box. GBrain does that, and adds two things nobody else ships together:

• 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 self-wiring knowledge graph. Every page write extracts entity refs and creates typed edges (attended, works_at, invested_in, founded, advises) with zero LLM calls. Ask "who works at Acme AI?" or "what did Bob invest in this quarter?" and get answers vector search alone can't reach. Benchmarked: P@5 49.1%, R@5 97.9% on a 240-page Opus-generated rich-prose corpus, +31.4 points P@5 over its graph-disabled variant and over ripgrep-BM25 + vector-only RAG by a similar margin. Full BrainBench scorecards live in the sibling gbrain-evals repo.

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.

~15 minutes to a working personal agent on the recommended Codex / Claude Code path (mostly a short interview); ~30 minutes for the always-on OpenClaw / Hermes setup. Database ready in 2 seconds either way (PGLite, no server).

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:

…

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

[!WARNING] GBrain is NOT distributed on npm. The npm package named gbrain is an unrelated package with no connection to this project. Do not run npm install -g gbrain or bun add -g gbrain — you'll get something else, and it can shadow the real binary on your PATH. Install and upgrade ONLY via the documented paths below (bun install -g github:garrytan/gbrain, or git clone + bun install && bun link). If you already ran the npm install by mistake: npm uninstall -g gbrain / bun remove -g gbrain, then reinstall from GitHub. gbrain doctor detects a shadowing npm install and prints the fix.

GBrain is designed to be installed and operated by an AI agent. New to GBrain? Start with Codex — it runs on the ChatGPT subscription you already have, takes ~15 minutes, and deploys nothing. Already living in Claude Code? Its path is identical. Want GBrain running the way it was designed to run — always on, enriching your brain around the clock? That's OpenClaw or Hermes, at real server + API cost. Each path below is complete on its own. (Wiring it up by hand instead? Jump to CLI standalone or the MCP table.)

For Codex — the recommended first step

Turn Codex into your persistent personal agent. (Just want the brain + skills without the full agent? codex plugin marketplace add garrytan/gbrain@codex-plugin then codex plugin add gbrain@gbrain — see docs/mcp/CODEX.md. The paste block below builds the whole agent.) Works in the ChatGPT desktop app (open Codex on a folder) and in the Codex CLI (codex in a terminal) — same install, same result. Open Codex in a new, empty folder (not an existing code project) — that folder becomes your agent's own private GitHub repo, which bootstrap creates and privacy-verifies for you. Then paste:

Read and follow every step of:
https://raw.githubusercontent.com/garrytan/gbrain/latest-stable/BOOTSTRAP_FOR_AGENTS.md
Goal: set yourself up as my persistent personal agent in this folder, with gbrain
as your memory. Interview me before writing any identity file — never invent
answers. Ask before anything destructive. You are not done until
`gbrain bootstrap verify` exits 0.

Codex will ask for command approvals during the install — approving them is the sandbox working as intended. What you get, in about 15 minutes: a short interview (6 required questions) → your agent's identity (SOUL.md, USER.md, MEMORY.md) rendered from your own answers, never invented → a local PGLite brain (2 seconds, no server, no Docker) → MCP wired so every session can search and write memory → a private GitHub repo, created and privacy-verified, as your agent's durable body. Works with zero API keys — keyword search plus memory your agent writes itself; one optional key upgrades capabilities (OpenAI: semantic search + automatic fact extraction; Voyage: semantic search; Anthropic: fact extraction). Codex reads brain context through its tools each turn (pull-based). The click moment: tell it one small thing to remember, restart Codex, then ask for it back — the answer comes from the brain, not from this chat's context (which the restart cleared). That cross-session round-trip is the whole product; "what's my name / my top jobs?" is answered from your identity files, which is nice but not the same trick.

Two things worth understanding once it's running: you own the brain — every memory is a markdown file in that private repo (read it, clone it to a second machine, delete it and the brain is gone) — and the first skill to run is cold-start: say "fill my brain" and your agent imports your Gmail, calendar, and contacts — via the native connector (gbrain google setup, tokens in gbrain's local credential vault, never held by the agent), via ClawVisor (a hosted OAuth gateway), or from offline archives like Google Takeout — one consented step at a time. An empty brain is a database; a filled one is a memory.

Prefer to make the repo yourself? Create a new empty private repo under your own GitHub account (no README/.gitignore/license), clone it, open the clone in Codex, and paste the same block — bootstrap detects your empty repo and adopts it instead of creating one. The repo must be empty and personal-account-owned; org-owned repos are refused (create one under your account, or let bootstrap make it).

For Claude Code — turn it into your persistent personal agent

Works in the desktop app and in the CLI (claude in a terminal) — identical harness, identical result. Open Claude Code in a new, empty folder (not an existing code project) — that folder becomes your agent's own private GitHub repo, created and privacy-verified for you. Then paste the same block:

Read and follow every step of:
https://raw.githubusercontent.com/garrytan/gbrain/latest-stable/BOOTSTRAP_FOR_AGENTS.md
Goal: set yourself up as my persistent personal agent in this folder, with gbrain
as your memory. Interview me before writing any identity file — never invent
answers. Ask before anything destructive. You are not done until
`gbrain bootstrap verify` exits 0.

Everything from the Codex path applies — interview, identity from your own answers, local brain, private repo, keyless mode — plus Claude Code gets per-turn context hooks (on by default, with an opt-out): your brain loads automatically into every prompt, and your work persists to your private repo on a per-turn cadence (debounced ~5 min locally, every turn in a cloud sandbox — this covers the /exit case the harness never fires a session-end hook on), with a notice on your next turn if a push ever fails. This works in a Claude Code cloud session too, not just on your laptop: verification falls back to pure git protocol when the sandbox blocks the GitHub API, and gbrain bootstrap cloud-setup-script prints the environment setup recipe. The click moment: tell it one small thing to remember, restart the session, then ask for it back — a fresh session has no chat context, so the answer can only come from the brain. That cross-session round-trip is the whole product ("what's my name?" is answered from your identity files — nice, but not the same trick). Same two follow-ups as the Codex path: you own the brain (markdown in your private repo), and cold-start is the first skill to run — "fill my brain" imports your email, calendar, and contacts (ClawVisor) or offline archives, one consented step at a time. Full contract, security posture, cloud sandboxes, and uninstall: docs/guides/bootstrap.md.

Prefer to make the repo yourself? Create a new empty private repo under your own GitHub account (no README/.gitignore/license), clone it, open the clone in Claude Code (CLI or the desktop app's open-a-repo flow), and paste the same block — bootstrap adop