cobrain
Create your brainGo to your brain
Shared memory for your AIs

Yoursecondbrain. ReadablebyyourAIs.

You can start from nothing. From then on every decision, constraint and useful detail stays in your Cobrain: Markdown notes that Claude, ChatGPT, Claude Code and any other compatible AI can read and update.

Create your brain, freeGo to your brainFree. We do not ask for a card, and it does not expire.
  • Claude
  • ChatGPT
  • Claude Code
  • and any AI that speaks MCP

Every time, you start over

You switch AI, open a new chat, bring in a colleague: every time you have to rebuild the context. Decisions scatter across conversations and people, and the work starts again from the beginning.

It is not that the models have no memory: it is that the memory is locked inside somebody else's product. You cannot see what is in it, you cannot correct it, you cannot take it with you.

You do not have to write it (but you can)

You connect your AI once. Whenever something comes up that will matter tomorrow too — a decision, a constraint, a contact — it can save it in your Cobrain. In the next conversation it is already there, even if you switch AI.

And everything stays open. They are Markdown files in real folders: you open one, fix a line, move a note, delete what you no longer want the AI to know.

A brain grows wider when it is not only yours

Share a folder, or even a single note, with a colleague. It shows up inside their brain and becomes context for their AI too.

The client, their decisions, their constraints: you work on them with Claude, your partner with ChatGPT, both of you on the same notes. Neither of you starts over.

The product

Here is where your memory lives

Folders on the left, the note in the middle, on the right who wrote it and when. The same things your AI sees.

app.cobrain.space
The Cobrain dashboard: the folder tree on the left, an open note in the middle, the panel showing who wrote in it on the right.
With your AIs

Just ask. The context is already there.

Keep using whichever AI you prefer. You ask the same question as always; it finds in your Cobrain the context you used to have to explain again.

How can I help you today?
+ChatCoworkOpus 5 Alto ⌄

Your AI cannot do more than you

The site and the AIs obey the same permissions, applied inside Cobrain itself. If you cannot see or change something, neither can your AI.

A branch you have not shared cannot be reached

Not by anyone, and not by any AI. You choose who comes in, and whether they can only read or write too.

You sign in with a link and a code by email

You get an email with a button and a code. They work once, and they expire.

You connect an AI once, and revoke it whenever you want

Each one works with your permissions: it sees nothing you would not see.

Every save keeps the one before it

Who changed what, and when — including when it was your AI. A wrong edit can be undone.

You write in Markdown, with all its levels

Headings, lists, quotes, code. Underneath they stay .md files: no format only we can read.

You take everything with you, whenever you want

An archive of folders and files. It opens with Obsidian, with a text editor, with anything. The data sits in Europe, in Ireland.

Free, really

The free plan is not a trial: you can genuinely build your brain on it. You move to Pro when you want to share and work on the same notes with other people.

Free

$0
  • A Cobrain of your own
  • Up to 1,000 notes
  • As many AIs as you want to connect
  • Folders, search, tags, export
  • Up to 3 shares, read-only
  • Branches received from others: unlimited, always
  • History: the last 2 versions, for 3 days
Create your brain, freeGo to your brain

We do not ask for a card, and it does not expire.

Pro

$9/month
  • Unlimited notes and brains
  • Share with as many people as you like
  • Whoever receives can write, not only read
  • Attachments and images in your notes: 2 GB, up to 10 MB per file
  • History: the last 30 versions, for 7 days
Go Pro

Only the sharer pays, never the receiver.

Team

$7/seat per month
  • Pro for the whole team, from 3 seats
  • The company’s Cobrain stays with the company
  • Assign and remove seats whenever you want
  • Everyone keeps their own Cobrain, with their own 2 GB of attachments, and leaves with it
  • A single invoice, in the company’s name
  • Monthly, or yearly with two months free
Go Team

Made for agencies, studios and small teams. Clients and collaborators who receive a branch still come in free.

Line by line, Team included: all the plans compared.

Questions

What people usually ask us before signing up.

Which AIs does it work with?

Claude, ChatGPT, Claude Code, Codex and any other AI that supports MCP. You paste an address and authorise once. Today Claude requires a paid plan for custom connectors; on ChatGPT you upload our plugin, a file you download, on any plan. Those are their requirements, not ours.

Do I need to have notes already?

No. Most people start from nothing and their Cobrain grows as they work. If you already have notes somewhere — in Notion, in a folder, in old chats or in Obsidian — your AI can bring them in: there is a guide.

Does the person receiving a share have to pay?

Never. A free account is enough. The plan is paid for by whoever shares.

What if I stop paying?

You lose nothing. All your notes stay, and shares already active keep working read-only. You go back to the free plan limits for anything new. Reactivate and everything picks up where it was.

Can I take everything with me?

Yes, whenever you like, in one go. They are .md files in folders: what comes out opens with anything.

Where is my data?

On servers in Europe, in Ireland. Every save keeps the previous version.

Free, no card needed

Start with a single note.

It is free and no card is needed. You sign in with a link sent by email, connect your AI and start building a memory that does not stay locked inside a chat.

Create your brain, freeGo to your brainA thousand notes, as many AIs as you want to connect.