Install
Installers for macOS, Windows and Linux, the first launch, your first agent, the app's language and how updates work.
Download the installer for your system from the releases page. The macOS build is signed and notarized by Apple. The Windows build is not signed yet, so Windows asks once before the first launch.
Open Kettu-<version>-arm64.dmg and drag Kettu into Applications. Kettu needs a Mac with Apple silicon.
Run Kettu-<version>-x64-setup.exe, or Kettu-<version>-arm64-setup.exe on Arm devices. When SmartScreen says “Windows protected your PC”, click More info, then Run anyway.
Download Kettu-x86_64.AppImage, or Kettu-arm64.AppImage on Arm. Make it executable, then run it:
chmod +x Kettu-x86_64.AppImage
./Kettu-x86_64.AppImage AppImages need FUSE 2: libfuse2, or libfuse2t64 on Ubuntu 24.04 and later.
On a server or a development machine without a desktop, install the daemon instead: curl -fsSL https://kettu.sh/install | sh.
First launch
Kettu has no account of its own, so there is nothing to sign in to. On macOS and Linux it reads PATH and your other variables from your login shell once, so it finds the same programs your terminal does. On Windows it uses the environment it was started with, and a change to PATH takes effect after you restart Kettu.
Install an agent
Kettu implements no agent itself. It runs the ones you install, with your own accounts and settings, so install at least one, such as Claude Code or Codex.
Open Settings › Harnesses to see every agent program Kettu knows and whether it is installed. For a missing one, Install lists the ways its maker documents, such as the official install script, Homebrew, WinGet or npm, shows the command and runs it. If you install it in your own terminal instead, click Reload environment at the bottom of that page so Kettu looks again.
Node.js
The first time you use Claude Code, Kettu installs the Claude Agent SDK with your npm, so Node.js with npm must be on PATH. The other agents Kettu installs from npm run on your Node.js, some only on version 22 or later. See Supported agents.
Language
Kettu follows your system: Simplified Chinese when your system prefers it, English otherwise. To choose, open Settings › General › Language and pick System, English or 简体中文. The change applies at once. What agents write is not translated.
Updates
Kettu checks for a new version 30 seconds after it starts and then every hour. By default the new version downloads in the background and installs when you quit. Once it is downloaded the sidebar shows Update ready, and Restart installs it right away. Your sessions and drafts come back after the restart.
To choose when updates download and install, open Settings › About › Automatic updates:
| Option | What happens |
|---|---|
| Download and install on quit | The default. Downloads in the background, installs when you quit |
| Download, install when I restart | Downloads in the background, installs only when you click Restart |
| Ask before downloading | Shows the new version with an Update button |
| Off: check only when I ask | Nothing until you click Check for updates |
On macOS, if you run Kettu from the disk image instead of Applications, Update first moves it to Applications. On Linux the AppImage replaces itself, so a launcher pointing at it keeps working.
Agents update on their own schedule, separately from Kettu. See Supported agents.