Your knowledge deserves a home, not a subscription.

Q: Where are my notes stored?

In a folder on your computer (~/Betelgeuse by default), as Markdown files in a git repository. Nothing leaves your machine unless you add a git remote to sync.

Notes, docs and databases as Markdown files you own, synced with git across all your devices.

Download — free Explore on GitHub30

macOS · Windows · Linux · Android preview · MIT licensed · No account required

The Betelgeuse editor on a computer, with the Welcome guide open

A roadmap database as a board on an Android phone

Works with
Claude Code
Cursor
Any MCP client
Obsidian
VS Code
git

Features

If you know Notion, you know this.

The blocks and databases you're used to, without the cloud: your pages are files on your own devices, and git keeps them in sync.

The slash menu, listing blocks to add to a page

Plugins

Make it yours.

Betelgeuse stays small. Add what you need from the plugin store, from personal finance to a library for your project files, or build your own.

One click from SettingsBrowse the store in Settings → Plugins and install. It's on straight away, and updates come on their own.
Signed and checkedStore plugins are built from source by the release pipeline and signed. The app refuses anything that doesn't match.
Only what they ask forEach plugin lists its permissions and gets nothing else. Turn it off and everything it added goes, with no restart.
Your data stays in your pagesWhat a plugin keeps lives in your workspace, synced with git, and stays if you ever remove the plugin.

FinanceAccounts and credit cards, transactions, monthly budgets, investments and your net worth, with charts. Import bank statements. Your money stays in databases you own.Desktop and phoneRead more →Media LibraryBrowse and search your footage, audio, photos and project files where they already are, with previews, and link project folders to the pages that plan them.DesktopRead more →

Build your own

TypeScript and React, a few files.

Build a plugin →

src/main.tsx

import { definePlugin } from "@betelgeuse/plugin-api";
export const { activate } = definePlugin({
  activate(ctx) {
    ctx.commands.register({
      id: "hello",
      title: "Say hello", // in ⌘K
      run: () => ctx.ui.toast("Hello!"),
    });
  },
});

MCP

Your AI agents, on your terms.

A built-in MCP server lets your agents search, read and update the pages you share.

Copy-paste setupClaude Code, Claude Desktop, Cursor or any MCP client.
You choose what they seeHidden pages stay out of every search and tool.
Every change can be undoneEach agent edit is its own git commit.
Read-only if you likeLet an agent read, but never write.

Settings that choose which pages AI agents can see

Claude Code

>Mark the MCP server done and add a task to write its docs
⏺betelgeuse · query_database  Roadmap
⏺betelgeuse · update_note     Roadmap/Ship the MCP server.md
⏺betelgeuse · create_note     Roadmap/Write the MCP docs.md
✓Done. Both are commits you can undo.

Agents see only what you share when they connect through the Betelgeuse MCP server. An agent you separately give access to the folder can read the files directly.

Open source

Built by people who believe your data should be free.

MIT licensed and developed in the open. Use it, change it, make it better.

devian-labs / betelgeusePublic

A beautiful workspace on plain Markdown and git, open to AI agents over MCP.

notes-app open-source productivity

30 stars 3 forks v0.5.0 MIT

TypeScript 61.7%
Rust 25.1%
JavaScript 7.8%
CSS 4.7%

Star on GitHub30 Fork

ContributeSet up in four commands. Start with a good first issue.Request a featureShare ideas and vote in Discussions.Report a security issuePrivately, and we'll reply within a week.SponsorHelp fund signed builds and development.

Up next

Faster full-text search
Formulas in databases
More plugins in the store
Signed builds for macOS and Windows
The iPhone app
Handling edits from you and an agent at the same time
Use it as a CMS. Connect an external database or spreadsheet, and edit a website's FAQs, blog posts or any content right here. Your changes update the source.

Hack on it

Run it locally in a few minutes.

Contributing guide →

Terminal

$git clone https://github.com/devian-labs/betelgeuse
$cd betelgeuse
$npm install && npm --prefix mcp install
$npm run app# starts the app with hot reload

FAQ

Questions, answered.

Something else? Ask on GitHub.

Is it really free?

Yes. It's open source under the MIT license, with no account, subscription or paid tier.

Where are my notes stored?

In a folder on your computer (~/Betelgeuse by default), as Markdown files in a git repository. Nothing leaves your machine unless you add a git remote to sync.

What can AI agents see?

Only what you share. Pages you hide are left out of agent searches, listings and every MCP tool. That boundary covers agents connected through Betelgeuse's MCP server. An agent you separately give access to the folder itself can read the files.

Which AI tools work with it?

Any MCP client: Claude Code, Claude Desktop, Cursor and others. The app gives you copy-paste setup for each.

What are plugins, and are they safe?

Plugins add features such as Finance or Media Library. Store plugins are built from source by Betelgeuse's release pipeline and signed, the app checks the signature before installing, and each plugin only gets the permissions it lists.

Can I use it on my phone, or on more than one computer?

Yes, with git. Connect your workspace to a private repository you control, and Betelgeuse syncs in the background on each computer and in the Android app (a preview). A page changed in two places between syncs keeps both versions, so nothing is lost.

Why does my computer warn me when I open it?

The builds aren't code-signed yet (certificates cost money). Confirm once and it opens normally, or build from source to skip the warning entirely.

What doesn't it do yet?

It's an early preview. Search is basic, databases don't have formulas yet, there's no sharing or comments, the iOS app isn't distributed yet, and if you and an agent edit the same page at the same moment the last save wins (git keeps both).

Take your notes home.

Free. Open source. Yours to keep.

v0.5.0 · released Oct 15, 2026 · What's new

macOS

Apple Silicon and Intel

Apple Silicon 9 MB Intel 10 MB

Windows

Windows 10 and 11

Installer (.exe) 6 MB .msi 8 MB

Linux

AppImage and .deb

.AppImage 85 MB .deb 9 MB

Android

Android 8 and later · preview

.apk

Before you install: builds aren't code-signed yet, so your OS asks you to confirm the first time. On macOS, open System Settings → Privacy & Security and click Open Anyway. On Windows, click More info → Run anyway. Building from source avoids both. On Android, allow installs from your browser when asked. All releases

Build from source No warnings

Needs git, Node.js 20+ and Rust. The script checks for anything else.

$git clone https://github.com/devian-labs/betelgeuse && cd betelgeuse && ./scripts/install.sh

>git clone https://github.com/devian-labs/betelgeuse; cd betelgeuse; .\scripts\install.ps1

Tried it? Tell us what worked and what didn't.