# Knowtarium

> Knowtarium is an end-to-end encrypted knowledge base that people and their own AI agents work in over MCP. Notes are markdown in the Open Knowledge Format (OKF), organised in workspaces and folders. Every change is signed by whoever made it, person or agent, is kept in the history and can be undone in one click. Knowtarium can't read the notes.

Canonical site: https://knowtarium.com
Web app: https://app.knowtarium.com (sign up free at https://app.knowtarium.com/sign-up)

## What it does

- Encrypts notes, titles, file names, links and folder names on the device before they reach the server. The server sees the email, plan, storage used, file sizes, timestamps and how notes and folders nest (by ID, not by name).
- Lets AI agents (Claude Code, Codex, Cursor, OpenCode, Claude Desktop, VS Code) search, read, create and edit notes over MCP. Each agent gets one workspace, optionally only some folders, read or read-write, and optional permissions to move or delete notes and change folders.
- Signs every change with the key of the person or agent who made it, and keeps it in a version history with diffs and one-click undo.
- Optional review ("Ask me first") per workspace or folder: agents' changes there wait for approval.
- Folder instructions: what people write for a workspace or folder, which every connected agent follows there. Agents can only propose changes to them.
- Imports an Obsidian vault or an OKF bundle, and exports everything as plain markdown.
- A web clipper for Chrome saves pages, encrypted, to a workspace's Inbox: https://chromewebstore.google.com/detail/lfefajehibmoghhmijdhmihccbapjlkp

## Connect an agent

- `npx knowtarium connect` (Node.js 20 or later) opens the browser to approve the computer, then adds Knowtarium to the agents it finds. Details: https://knowtarium.com/agents#connect
- Claude Code and Codex plugin: https://github.com/Knowtarium/knowtarium-plugins
- Claude Desktop extension: https://github.com/Knowtarium/knowtarium-sdk/releases/latest/download/knowtarium.mcpb
- The CLI and MCP server are open source: https://github.com/Knowtarium/knowtarium-sdk

## Setup pages

- [Connect Claude Code to an encrypted knowledge base over MCP](https://knowtarium.com/agents/claude-code): Set up Claude Code with one command or the plugin, choose what it reaches, and check or undo what it changes.
- [Connect Codex to an encrypted knowledge base over MCP](https://knowtarium.com/agents/codex): Set up Codex with one command or the plugin, choose what it reaches, and check or undo what it changes.
- [Connect Cursor to an encrypted knowledge base over MCP](https://knowtarium.com/agents/cursor): Set up Cursor with one command or one click in the app, choose what it reaches, and check or undo what it changes.
- [Connect Claude Desktop to your notes over MCP](https://knowtarium.com/agents/claude-desktop): Set up Claude Desktop with the extension, no terminal needed, choose what it reaches, and check or undo what it changes.

## Pages

- [Home](https://knowtarium.com/): What Knowtarium is, how agents work in it, the history and undo, and the FAQ.
- [Features](https://knowtarium.com/features): Workspaces and folders, the editor, version history with diffs, one-click undo, optional review, search and the graph.
- [Agents](https://knowtarium.com/agents): Connecting Claude Code, Codex, Cursor, OpenCode, Claude Desktop and VS Code over MCP, what agents can and can't do, permissions and folder instructions.
- [Open Knowledge Format (OKF)](https://knowtarium.com/okf): The open markdown format Knowtarium stores notes in, with provenance, trust and freshness in frontmatter.
- [Security](https://knowtarium.com/security): How the end-to-end encryption works, what our servers can and can't see, and the known limits.
- [Pricing](https://knowtarium.com/pricing): The plans, their storage and workspaces, and the pricing FAQ.
- [Support](https://knowtarium.com/support): Email support, bug reports and reporting a security problem.
- [Guides](https://knowtarium.com/guides): All guides and explainers.
- [Compare](https://knowtarium.com/compare): All comparisons with other knowledge apps.

## Guides

- [Company brain: what it is and how to build one for AI agents](https://knowtarium.com/guides/company-brain): The shared memory people and AI agents work from, and how to build one as files your agents maintain.
- [AI second brain: notes your agents write and you can trust](https://knowtarium.com/guides/ai-second-brain): Notes your agents write and link for you, without losing track of what's true and who wrote it.
- [LLM wiki: how to build one and keep it accurate](https://knowtarium.com/guides/llm-wiki): Karpathy's agent-maintained wiki, set up step by step, plus the review layer it's missing.
- [Claude Code second brain: setup and review workflow](https://knowtarium.com/guides/claude-code-second-brain): Run Claude Code in your notes folder or Obsidian vault, and see and approve what it changes.
- [How to review what AI agents change in your notes](https://knowtarium.com/guides/review-agent-edits): Git, permissions and a review workflow that catches bad edits before you rely on them.
- [AGENTS.md and CLAUDE.md for a knowledge base](https://knowtarium.com/guides/agents-md-for-knowledge-bases): What to put in the instructions file your agents read, with a template to copy.
- [How to make AI agents cite sources in your knowledge base](https://knowtarium.com/guides/cite-sources): Require a source for every claim, record it in frontmatter, and check it with a second agent.
- [Migrate an Obsidian vault to OKF and keep using Obsidian](https://knowtarium.com/guides/migrate-obsidian-vault): What changes, what stays the same, and how to keep using Obsidian afterwards.

## Comparisons

- [Obsidian alternatives in 2026](https://knowtarium.com/obsidian-alternatives): Nine Obsidian alternatives, and which one fits working with AI agents.
- [Knowtarium vs Obsidian](https://knowtarium.com/vs/obsidian): Obsidian is built for a person writing notes. Knowtarium is an encrypted knowledge base your agents work in, with every change signed and undoable.
- [Knowtarium vs Basic Memory](https://knowtarium.com/vs/basic-memory): Both give AI agents a markdown knowledge base over MCP. Where they differ: encryption, signed history, review and teams.
- [Knowtarium vs Notion](https://knowtarium.com/vs/notion): A cloud workspace with AI built in, or an end-to-end encrypted knowledge base your own agents work in.
- [Knowtarium vs Logseq](https://knowtarium.com/vs/logseq): An open-source app for writing your own notes, or an encrypted knowledge base your agents work in.
- [Knowtarium vs NotebookLM](https://knowtarium.com/vs/notebooklm): Google's research notebook, now Gemini Notebook, or a lasting, encrypted knowledge base your own agents work in.
- [Knowtarium vs Slite](https://knowtarium.com/vs/slite): A team knowledge base in the cloud, or a personal, end-to-end encrypted one your agents work in.
- [Knowtarium vs Mem](https://knowtarium.com/vs/mem): An AI notes assistant that reads your notes, or an encrypted knowledge base your own agents work in.

## Pricing

Free with 500 MB and one workspace; Starter $5.99 a month for 2 GB, Pro $11.99 a month for 10 GB; two months free billed yearly. Every plan has every feature and is end-to-end encrypted. Paid plans are bought inside the app. Details: https://knowtarium.com/pricing

## Contact

support@knowtarium.com

## Optional

- [Privacy policy](https://knowtarium.com/privacy)
- [Terms](https://knowtarium.com/terms)
- [Refunds](https://knowtarium.com/refunds)
- [Imprint](https://knowtarium.com/imprint)