Your notes, end-to-end encrypted. Claude Code, Codex and Cursor read and write them, and every change they make is marked and one click from undone.
We can't read your notes. The AI you connect sees what it reads. What we can and can't see
Your knowledge base
Fernhill
Fernhill / product
Pricing
SavedFernhill sells two plans, Team and Pro, billed monthly or yearly. See Plans for what each includes.
Pro is €14 per month since September. Revenue by plan is in Revenue, and why customers leave goes in Churn reasons.
Plans
The search index, backlinks and the graph are built in your browser, and links keep working when you rename a note. Dashed ghosts are notes that are linked but not written yet. Our servers can't search your notes.
Import an Obsidian vault or an OKF bundle, as a folder or a zip. Export every workspace as plain markdown in one zip, whenever you like.
Each workspace has its own key, and every note is plain markdown in OKF, an open format any editor, script or agent can read. How Knowtarium uses OKF
Works with your agents
Knowtarium runs no AI of its own: these agents connect to it over MCP. Chat apps that only run in the cloud will connect later, through a hosted connector that decrypts only inside a sealed enclave running published code.
Knowtarium Web Clippera browser extension for Chrome: save the page you're on to your inboxIn practice
Run , pick a workspace in the browser, or just some of its folders, and click Allow. It lists the agents it finds on your computer, sets up Knowtarium in the ones you keep ticked, and nothing secret is copied or pasted.
From then on your agent searches and reads only what it needs, and writes straight into your workspace, following the instructions you wrote for each folder.
Example terminal session: npx knowtarium connect connects a workspace, then lists the agents it found (Claude Code, Cursor and Codex), all ticked; Cursor is unticked, so Knowtarium is added to Claude Code and Codex. Then Claude Code, asked to update a price, searches the notes and edits two of them.
History and undo
Pricing · History
Older versions are removed after 30 days, unless an open proposal still needs them.
Each workspace keeps older versions for as long as you set, from a day to a year: 30 days unless you change it. Try it here.
After 30 days, a version’s content is removed. The history still shows who saved it and when.
Restore any version in one click, or undo an agent's edit. Either way a new version is saved, signed by you. Nothing is overwritten, so you can always go back to what came before.
Agent edits
Fernhill / product
Pricing
Edited by Claude Code·2 minutes ago·See changes·Undo
Fernhill sells two plans, Team and Pro, billed monthly or yearly.
Pro is €14 per month, or €140 a year.
Prices exclude VAT. Revenue by plan is in Revenue.
What an agent changed is highlighted the first time you open the note.
Changes by Claude Code
What Claude Code changed on Oct 10, 2026, 9:41 AM, from the version before.
Details changed: generated
Edited by agents
On the workspace page, for the last two weeks.
Each agent signs its changes with a key made on your computer when you connected it, and your devices check every signature. Nobody, Knowtarium included, can forge who made a change.
Moving and deleting are separate permissions, off by default. Every delete is signed by the agent and listed with Undo for two weeks, or your history period if that's shorter, and a deleted note comes back while your history period keeps it.
Review, when you want it
Agent changes
How changes from connected agents land in this workspace.
Folders with their own setting
Review queue
Northwind
Proposed by Claude Code Oct 10, 2026, 9:41 AM · 1.2 KB · +1 −1 lines
Why, in the agent’s words: “Northwind renewed for two years.”
A rejection takes a comment, and the agent reads it next.
Optional review
An agent edits, you check
claude-code/2.1
Rewrites the note and checks the notes connected to it.
unverifiedwaiting for you
human:you
You read the diff and approve it, or send it back with a comment.
You edit, an agent checks
human:you
You change a fact in the note yourself.
human-reviewedagent check pending
claude-code/2.1
Checks every connected note, and proposes fixes where something no longer matches.
A person and an agent both checked the note after its last change. This is what your agents can rely on.
generated: { by: human:you, at: 10:00 } verified: - { by: human:you, at: 10:00 } - { by: claude-code/2.1, at: 10:04 }
Then time passes. With review on or off, once a note is past its stale_after date, it turns yellow until someone refreshes it.
Colour only ever means state
And more
Notes past their stale_after date get a stale mark, so you can see what needs a refresh, with review on or off.
Titles, paths and the full text of every note, as you type. The index is built in your browser, so we never see a query.
Click a citation to see the source behind it and who made it.
Links to notes nobody has written yet show up as dashed ghosts: a to-do list for your agents.
Bring in an Obsidian vault or an OKF bundle, and export every workspace as plain markdown files in one zip.
Step away (15 minutes by default) or lock it yourself, and your keys are cleared from memory until you type your password again.
End-to-end encrypted
Encrypted on your device before it reaches us, with keys only you and your agents can unlock.
What we need to run your account and sync your notes.
The AI you connect sees what it reads. We run no AI models, so nothing is sent to a model on our behalf. Your agent decrypts notes on your own computer, and whatever it reads goes to its AI provider, like anything else you give it. Connect only the agents you trust, and give each one only the folders it needs.
Because we can't unlock your keys, if you lose both your password and your recovery key, we can't recover your notes.
Pricing
Every account starts on Free, with 500 MB of storage, one workspace and every feature. When you need more room, Starter is $5.99 a month for 2 GB and up to 5 workspaces, and Pro is $11.99 a month for 10 GB and unlimited workspaces. Billed yearly, you get two months free. You upgrade inside the app, and every plan is end-to-end encrypted and works with your own agents.
$0a month
Nothing to pay
The whole app, for one workspace.
$5.99a month
Billed monthly
For when your notes outgrow the free plan.
$11.99a month
Billed monthly
For big knowledge bases and many workspaces.
Prices in USD. VAT included where it applies; US and Canadian sales tax added at checkout.
FAQ
No. Your notes, titles, file names, links and folder names are encrypted on your device before they reach us, and only you and the agents you connect can unlock the keys that open them. We see your email, your plan and billing status, how much storage you use, file sizes, timestamps, and how notes and folders nest (by ID, not by name). The agents you connect, and their AI providers, see what they read.
How the encryption worksClaude Code, Codex, Cursor, OpenCode, Claude Desktop and VS Code. One command (npx knowtarium connect) adds Knowtarium to the ones it finds on your computer, all but VS Code. Cursor and VS Code can add it in one click in the app, Claude Code and Codex can install the plugin, and Claude Desktop the extension. Each agent gets one workspace, optionally only some folders, and read or read-write access, plus optional permissions to move and delete notes and to organize folders, which you can change later. Connectors for claude.ai and ChatGPT are coming later.
How agents connectEvery change shows who made it and is kept in the history, so you can undo it in one click. Agents can delete only if you gave them that permission, and a deleted note comes back with Undo while your history period keeps it. If you'd rather approve changes first, turn on Ask me first for a workspace or a folder, and agents' changes there wait for your approval.
Yes. Write instructions for the whole workspace or for any folder (Edit instructions, in the folder's menu), or start from a template: Market research, Meeting notes or Decision log. Every agent you connect follows them for each note it writes there, the workspace's first and the folder's own last. Agents can only propose changes to your instructions, which wait for you in the review queue, and only instructions you saved or accepted apply.
How folder instructions workYes, with the Knowtarium Web Clipper, a browser extension for Chrome. Click its button (or press Alt+Shift+S, Option+Shift+S on a Mac) to open it, add a note or a category if you like, and press Save. The page's link and title wait, encrypted, until Knowtarium is next open on that workspace or a connected agent that can write to the inbox runs, and are then filed as a note in that workspace's Inbox. The extension can't read your notes.
About the web clipperYour recovery key, shown once when it's made, gets you back in. If you lose both, we can't recover your notes: that's what end-to-end encryption means.
Yes. Import an Obsidian vault or an OKF bundle into a workspace, as a folder or a zip. You can export everything as plain markdown files whenever you like.
It's free to start: 500 MB of storage and one workspace, with every feature. When you need more room, Starter ($5.99 a month) and Pro ($11.99 a month) add storage and workspaces, with two months free when billed yearly, and you upgrade inside the app.