Get Callosium

The core is free, forever, and open source under Apache-2.0. It runs on your own machine and your notes stay in a folder you choose.

Mac, Linux and Windows — one command

You need Node.js 20 or newer. Then:

npm install -g callosium
callosium

callosium opens the dashboard in your browser and walks you through choosing a folder and connecting your first AI. If you would rather not install anything permanently, npx callosium runs the same thing once.

What happens on first run

Callosium downloads a small open-source language model (about 130 MB, one time) so meaning-based search works offline afterwards. Keyword search works immediately, before the download finishes, and everything keeps working with no internet once it is done. See the privacy policy for exactly what touches the network.

Windows desktop app

There is a native Windows build, but it is not code-signed yet, so Windows Smart App Control will block it and there is no "run anyway" for that. Until the certificate is in place, the command above is the supported route on Windows. Signed builds are planned for September.

Source

The engine, the MCP server and the dashboard are all in one repository: github.com/callosium/callosium. The benchmark generator ships with it, so you can reproduce the accuracy numbers yourself.