Second brain · MCP connector · Swiss company · database in Switzerland
Your second brain.
Readable by every AI.
Markdown notes connected by links. A living graph as your home screen. One connector that lets Claude, ChatGPT and any MCP client read and write your notes like a teammate.
Free for 14 days · CHF 12 / month · Export anytime
01
Obsidian, but in the cloud
Every note is a Markdown file. [[Wikilinks]], backlinks, frontmatter, folders and tags behave exactly like you expect. Import your vault as a zip, export it back whenever you want. No lock-in, by design.
02
The graph is the home screen
Open Firn and you see the shape of your thinking, not a file list. Click a node to read beside it. When an AI writes, the node lights up — you can watch where thinking happens.
03
One connector for every AI
Firn runs a remote MCP server with OAuth 2.1. Paste one URL into Claude, ChatGPT, Cursor or Le Chat and approve access. Then paste the standing instruction so every chat checks Firn first and saves what matters. Every AI change is logged and undoable.
Connector
Give your AI a memory it can be trusted with.
- • Read-only or read & write, for the whole brain or chosen folders.
- • A rules note tells every connected AI how your brain is organised and how to write.
- • Full history: which client changed what, when — one click to undo.
- • Deleting is only ever moving to the trash.
- • Revoke a client any time; its tokens stop working immediately.
→ context
Rules: search first, edit minimally, new notes go to Inbox/.
→ search "pricing experiments 2026"
3 results · Projects/Firn pricing.md › Hypotheses
→ edit_note replace_section "Hypotheses"
✦ Projects/Firn pricing.md updated · revision 14
Security
A second brain holds what you show nobody. It is stored accordingly.
01
One brain per account, sealed
Every note, revision, link and attachment carries your brain's ID. Every query is bound to it and to your session. There is no path from one account to another's data.
02
Encrypted, backed up, exportable
Your notes live in a PostgreSQL database at Exoscale in Switzerland (Zurich or Geneva), operated by a Swiss company under Swiss data protection law. The database and its backups are encrypted at rest; your notes stay plain Markdown and leave as a ZIP whenever you want.
03
AIs get a key, never your login
OAuth 2.1 with PKCE, read-only or read & write, whole brain or chosen folders. Tokens expire after an hour and die the moment you revoke a client.
04
Nothing trains on your notes
No provider, including us, uses your content to train models. Every change an AI makes is a revision with a diff and an undo; deleting only ever moves notes to the trash.