Koru for developers
A notes app for developers, with your terminal in the next tab
Koru is a free, open-source notes app for developers. Write docs with real code blocks, open your shells as tabs beside them, and let AI tools read and edit your notes through Koru’s local MCP server. It is a native app written in Rust, works offline, and keeps your workspace on your machine.
Why do developers need a different kind of notes app?
Developer notes are half prose and half code: a design doc with a schema in it, a runbook with the commands to paste, a scratch file next to the terminal you are pasting into. Most note apps treat code as an afterthought, keep the notes in someone else’s cloud, and live in a different window from your shell.
Koru puts documents, files and terminal sessions in one native window, as tabs. Your notes stay on your disk, open instantly and work on a plane.
Do code blocks work like code?
Yes. Type three backticks at the start of a line and it becomes a code block. Inside it, Enter adds a line instead of a new block, and the block keeps its language.
- A language chip on each block picks the grammar for syntax coloring, or Auto.
- Coloring is computed from the text and the theme, never stored, so it does not bloat your notes or your sync.
- One click copies the block’s source.
- Inline code: select text and press the backtick key, or Ctrl+Shift+C (Cmd+Shift+C on a Mac).
- Markdown import keeps fenced code and turns YAML front matter into a YAML code block. Export back to Markdown at any time.
Can I keep a terminal next to my notes?
Yes. Press + at the end of the tab strip, or Ctrl+Shift+A (Cmd+Shift+A on a Mac), and pick Shell. On Windows that is Command Prompt, PowerShell or Git Bash; on a Mac, your login shell, PowerShell or Bash. A shell session belongs to your machine, not the tab: close the tab and the session keeps running, and you can reopen it from the same menu.
On a Mac, the menu also offers the coding agents you have installed, such as Claude Code, Codex and OpenCode, and each session opens as its own tab beside your notes. Agent tabs come to Windows in an upcoming release; until then, run any command-line agent in a shell tab.
How do AI tools work with my notes?
Koru includes an MCP server that runs on your own machine. Connect an MCP client to it, such as Claude, ChatGPT or a local model through Ollama, and it can search, read and edit your workspaces. With a local model, nothing leaves your computer.
Setting it up is manual today: you add koru-mcp, which ships beside the app, to your MCP client’s configuration. Koru does not ask per client, so connect only tools you trust. Step-by-step guides for Claude, ChatGPT and Ollama are in the repository.
Koru does not lock you into one AI provider, and it does not send your notes anywhere on its own.
Can I build on Koru?
Yes. Besides MCP, Koru exposes a local API, served by the Koru app on your device, so you can write scripts and tools that work with your workspace directly. The API’s wire schemas and the MCP tool reference are in the repository. Detailed developer documentation is coming soon.
Is Koru open source?
Yes. The Koru app is open source under the Mozilla Public License 2.0, on GitHub. It is written in Rust: parley for text layout, vello for GPU rendering, winit for windows, iroh for device-to-device connections and Loro, a CRDT, for conflict-free sync. Clone it, run koru.bat setup and koru.bat run on Windows (or ./koru.sh on macOS), read what it does with your notes, and send a pull request. Every commit is signed off under the Developer Certificate of Origin.
Where does my data live?
On your machine. Koru stores workspaces locally, works with no connection and no account, and syncs between your devices directly, peer to peer, end-to-end encrypted. Usage telemetry is off until you agree to it, and never includes your documents. A build from source can remove the telemetry destination entirely with KORU_TELEMETRY_ENABLED=0.
Keyboard shortcuts worth knowing
| What it does | Windows | Mac |
|---|---|---|
| Open Add…, for a shell or a document | Ctrl+Shift+A | Cmd+Shift+A |
| Search everything, from anywhere on the computer | Ctrl+Shift+K | Ctrl+Shift+K |
| Turn the line into a code block, or back | Ctrl+` | Cmd+` |
| Leave a code block | Ctrl+Enter | Cmd+Enter |
| Hold to dictate (Koru Voice) | Ctrl+Shift+D | Cmd+Shift+D |
What’s coming for developers?
On the roadmap: chat with your own AI provider, a hosted Koru AI chat, delegated agent runs, a Cloud API and Cloud MCP. None of these is in the current release.
Questions
Is Koru a Markdown editor?
Not exactly. Koru has its own document model, stored locally and synced as a CRDT, rather than a folder of .md files. It imports Markdown and TextBundle, and exports either at any time, so your notes are never locked in.
Can I run Claude Code or Codex inside Koru?
Yes. On a Mac, pick them from the + menu and each opens as a tab beside your notes. On Windows, run them in a shell tab until agent tabs arrive in an upcoming release. To let an AI tool read and edit the notes themselves, connect it to Koru’s local MCP server.
Does Koru work offline?
Yes. Everything is stored on your machine, so writing, search and your shells work with no connection. AI tools still need whatever connection their own model needs.
Which platforms does Koru run on?
Windows, and macOS on Apple silicon. A Linux app is coming soon, and the iOS and Android apps are in development.
Is Koru free for commercial use?
Yes. Koru is free with no account, and the MPL-2.0 license allows commercial use. If you change Koru’s own files and distribute them, those files stay open; your own files beside them can use any license.
Can I build Koru from source?
Yes. The README lists what you need: Rust via rustup, sccache, a GPU with DirectX 12, Vulkan or Metal, and Python 3. Then run the setup and run commands for your platform.
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