claudius

claudius makes music the way a producer does in a DAW. It picks sounds, writes drums, bass, chords and melodies with music theory, arranges them into a song with builds and drops, mixes and masters it, listens to the result, and changes what it does not like.

Every sound is real audio: synthesized in code, or recorded (a grand piano, a Rhodes, string sections, real TR-808 and TR-909 drum machines, Apple Loops, your own files). There is no neural audio generation and no General MIDI. After every change, a critic judges the song (loudness, tonal balance, the energy of the arrangement, music theory, and what an audio model hears) and says what to fix.

You can work with it in a studio app, in a small script language, through an assistant such as Claude or ChatGPT, or from the command line.

Website · Documentation · Releases

Install

Download Claudius from the website or the releases page:

• Mac: the disk image for Apple silicon or Intel. Open it and drag Claudius into Applications (the first time you open it).
• Windows: the .msi, which puts Claudius in the Start menu.
• Linux: the .deb, the .rpm or the AppImage.

The studio downloads its listening models by itself the first time it opens, and offers the sample packs. From a terminal instead:

curl -fsSL https://github.com/devlato/claudius/releases/latest/download/install.sh | sh    # macOS (the app too), Linux
irm https://github.com/devlato/claudius/releases/latest/download/install.ps1 | iex          # Windows (PowerShell)
claudius setup    # sample packs and listening models, about 4 GB to download

You can also build it from source; see install.

A first look

claudius make --genre lofi          # a finished song in ./out/lofi-<title>-<seed>/song.wav
claudius studio                     # the studio, with the engine inside
claudius connect claude-desktop     # MCP and skills; then ask Claude for a song while you listen

Your assistant's own command works too: claude mcp add --scope user claudius -- claudius mcp, codex mcp add claudius -- claudius mcp, or Cursor's install link (the assistant's own command). Claude Code's plugin brings the skills along (claude plugin marketplace add devlato/claudius, then claude plugin install claudius@claudius), and on a Mac the release's claudius-<version>.mcpb adds Claudius to Claude Desktop.

A song in the script language:

blank("lofi"); tempo(84); key("D minor"); swing(0.58);
prog("A", "Dm9 Gm9 Bbmaj7 A7");
track("drums", s("bd ~ ~ bd, ~ sd, hh*8?0.15").bank("tr808"));
track("keys",  chord("prog").voicing(50, 72).s("rhodes").room(0.3));
track("bass",  chord("prog").root().struct("x ~ ~ x ~ x ~ ~").s("upright_bass"));
form([sec("intro", 4, "keys"), sec("groove", 16, "*"), sec("break", 8, "keys"), sec("groove", 16, "*")]);

claudius script song.rhai renders it and prints the verdict. Any song claudius makes prints back as a script like this, so a script is also the way to read a song.

Documentation

• Your first song, then learn to make music if you have never made any.
• claudius for DAW users and the language reference if you have.
• Working with an assistant (MCP and skills: Claude, ChatGPT, Cursor, Codex).
• Architecture, design decisions and a tour of the repository for working on claudius.

The book's pages are in docs/src; cargo xtask site builds them into a website with mdBook.

Privacy

claudius sends nothing about you or your music anywhere. Anonymous usage statistics (the command, the version, the system, where a setup or a crash failed) stay off unless you say yes when the studio asks, or run claudius telemetry on; privacy lists every field.

Contributing

See CONTRIBUTING.md. Security reports go through GitHub's private reporting, described in SECURITY.md.

Licence

claudius is MIT-licensed (LICENSE). The sample packs and listening models it downloads have their own licences, all of which allow making and publishing music; NOTICE lists them.