Your extended brain

A zero-friction personal knowledge base that builds itself.

Save articles, PDFs, and notes with one click. BrainExtension organizes them, connects the dots, and lets you ask it anything, from your browser, your phone, or any AI agent. No tagging. No setup. Just capture.

Join the waitlist See how it works

What is an extended brain?

A second mind that grows every time you feed it.

You feed it.

Save a webpage with the extension, drop a PDF, paste a note, forward an email. One click, no tagging required.

It connects the dots.

Every memory is auto-chunked, summarized, and linked to related ones via typed synapses. Your brain literally grows a graph.

You ask it anything.

Chat with it like a person who has read everything you have, and remembers what you intend to do next.

Why it’s different

A knowledge base that thinks with you.

Capture from anywhere

Chrome extension, web dashboard, PDF drop, paste a note, forward an email. One click, no tagging.

Synapses & smart connections

Memories auto-link via typed, directed connections. Navigate by association, the way your real brain does.

Remembers what you intend

Schedule prospective memories like "revisit this paper next Tuesday". Habits emerge from your patterns.

Built for agents

API + MCP server. Plug your brain into Claude, ChatGPT, OpenClaw or any custom agent as native context.

Under the hood

Built like a brain, not a filing cabinet.

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Memories

Web pages, PDFs, and notes auto-chunked into small pieces for precise search.

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Synapses

Typed connections between memories form a knowledge graph you can navigate.

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Engrams

AI summaries give your brain instant context - no search needed.

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Intentions

Future reminders and habits live alongside your knowledge, not in a separate app.

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Layered recall

Four retrieval layers surface the right info at the right time, fast and cheap.

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Agent-ready

API + MCP server let any AI agent tap into your brain as native context.

Brains people are growing

Research dossierCompetitive intelLearning brainContent pipelineLead researchRecipe vaultTravel planningReading queue

Talk to your brain

It answers from what you actually know.

Research

that stanford long-context rag paper from march - main args again?

Got it: “Long-Context RAG: Limits and Tradeoffs” (saved Mar 14).
1. Recall plateaus past 32k tokens.
2. Re-ranking matters more than chunk size.
3. Hybrid lexical+vector beats pure vector on long docs.

Recipe

pasta recipe marco sent me last summer, the one w anchovies + breadcrumbs

That’s pasta con la mollica, forwarded by Marco on Aug 12. Saved in your “Sicilian dinners” brain. Want me to scale it for 4?

Follow-up

wtf did i promise sarah again 😅

Two open threads with Sarah:
1. Send her the Q2 hiring plan(you said “by Friday” on Apr 3).
2. Intro her to James at Linear.
Want me to draft the email?

same conversation works in Claude, ChatGPT, Telegram, or your own agent, via API + MCP

Pricing

Start free. Scale when you need to.

Free

Forever free

✓ 1 brain
✓ 100 memories per brain
✓ 50 AI chats / month
✓ Synapses & graph view
✓ Chrome extension

Join the waitlist

Individual

$9/month

or $90/year (save 17%)

✓ 5 brains
✓ 1,000 memories per brain
✓ Unlimited AI chat
✓ API + MCP server
✓ Prospective memories
✓ Cross-brain discovery

Join the waitlist

Family

$19/month

or $190/year (save 17%)

✓ Up to 5 members
✓ 10 brains per member
✓ 5,000 memories per brain
✓ Shared family brains
✓ Everything in Individual

Join the waitlist

Start growing your extended brain.

We're putting the finishing touches on something great. Drop your email and we'll let you know the moment it's ready.