Obsidian is where your notes are born. Cobrain is where your AIs reach them.
Same format, same folders, same links. The difference is one word: a vault sits on your computer, and an AI reaches it only from there, only while that computer is on, and only when you are the one using it.
Let us start with what is the same
And it is nearly everything you like about Obsidian.
Cobrain did not invent a format: notes are Markdown files in real folders, with [[wikilinks]] and #tags. The vault you already have comes in as it is, and what comes out reopens in Obsidian with no conversion: our own brain started exactly like that, as a 648-note vault carried across in an afternoon.
If somebody tells you that you have to choose, they are selling you something. The real question is not which program you open to write: it is who else needs to read what you wrote.
The difference, in one line
A vault is a place. A brain is an address.
For a few months now a plugin has let Obsidian talk to Claude or Cursor: it runs a small server on your computer, and the AI, from that computer, reads the vault. It works, and it is the right thing to use if you always work there.
But it is that «on your computer» that decides everything else. Nothing runs while you are away. Claude on your phone cannot get there. Neither can ChatGPT on the web: it lives on a server on the other side of the world, and it does not have your disk. And the colleague you want to hand one folder to cannot have it without having all the rest.
Cobrain moves the same notes behind an address. From there every AI you speak to can reach them, from any screen, and so can the people you hand a branch to — with the permissions you set, applied by the database rather than by a program you have to trust.
Line by line
The first rows are the same for both: that is where an honest comparison starts.
| Obsidian + MCP plugin | Cobrain | |
|---|---|---|
| Note format | Markdown in folders | Markdown in folders |
| [[Wikilinks]] and tags | yes | yes |
| You can take them away | they are already files on disk | export everything, reopen it in Obsidian |
| Where they live | on your computer | on a server, reachable from anywhere |
| Your AI from the phone or the web | no: the vault is on the disk | yes, it is the same brain |
| While the computer is off | nothing | the AI still reads and writes |
| To connect an AI | a plugin, a key, a JSON file | an address and one authorisation |
| What the connected AI sees | the whole vault, or nothing | only what you see |
| Handing a folder to a colleague | the whole vault, with Sync | one branch, read or write, by email |
| If two write at once | the last save wins | appending is atomic; anything else stops and warns you |
| Who wrote a note | — | every note says who, when and from which AI |
| Version history | with Sync, or file recovery | included, on the free plan too |
| The editor | excellent, offline, a thousand plugins | essential, in the browser |
| Price | free; Sync $4/month; commercial use $50/year per person | free; Pro €9/month |
Obsidian prices checked in September 2026. Obsidian is free for personal use; Sync and the commercial licence are separate.
When Obsidian is enough
We would rather say it than have you find out later.
- You work alone, and always from the same computer.
- You use a single AI, the one running on that machine.
- You need the plugins, the graphs, the themes: there Obsidian has no rival, and we are not trying.
- You want the notes to stay only on your disk, with no server ever seeing them.
In all of those cases you do not need Cobrain, and there is no sense in paying for it.
When it stops being enough
It usually all happens at once, on a Tuesday.
- You open a second AI and realise it knows nothing of what the first one knows.
- You need something you wrote while you are away from your desk.
- Somebody joins: and you want to give them that client's folder, not your diary.
- You want to know who changed what — and to go back when an AI went too far.
They work together
It is not a migration, it is one more address.
Plenty of people keep Obsidian to write and Cobrain to be read: the notes that must stay private stay in the vault, the ones the AIs and colleagues need live in the brain. There is no format to convert in between, and no moment where you decide forever — if one day you stop, export everything and you are back to a folder of Markdown files, which is exactly what you had.
Questions
Can I import my vault?
Yes, as it is: folders, links and tags included. The guide covers the two minutes it takes. Our own brain started from a 648-note vault.
Obsidian already has an MCP plugin: what changes?
That the plugin runs on your computer. Your AI reaches it only from that machine, only while it is on, and it sees the whole vault. Cobrain sits behind an address: every AI gets there, from any screen, with your permissions.
Do I lose the plugins, the graph and the themes?
Yes, and we will not pretend otherwise: that is Obsidian's home ground. Cobrain has a plain editor, because its job is a different one — letting several AIs and several people read and write the same notes.
Do my notes sit on your server?
Yes: that is the price of making them reachable. They are encrypted at rest, permissions are applied by the database, and nobody uses them to train anything. The details are in permissions and privacy.
If I stop paying, do I lose everything?
No. Going back to free limits, it does not delete: the notes stay, and the full export is there on every plan.
Bring your vault, and keep it.
Import the folders you already have, connect your first AI and see in one afternoon whether it changes your day. It is free, and what goes in comes back out unchanged.
