claudius

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

Every sound is real audio. There is no neural audio generation and no General MIDI: drums and synths are synthesized in code, and the rest comes from recordings (a grand piano, a Rhodes, string sections, real TR-808 and TR-909 drum machines, Apple Loops if you have GarageBand, or your own files). Notes exist only as the score that plays those sounds, like a piano roll.

After every change claudius judges the song: is it loud enough and clean at the top, does the drop hit harder than the breakdown, are the bass notes on the chords, does it sound like the genre it claims to be? Each problem comes with what to change.

Four ways to use it

• The studio. An app with an arrangement view, step sequencer, mixer, harmony editor and script editor. It runs as a native window and in the browser. See the studio.
• Scripts. A small language in which a song is a few lines of code: track("drums", s("bd*4, [~ cp]*2")). Any song claudius makes can be printed as a script. See the language reference.
• An assistant. Connect Claude, ChatGPT or Cursor and ask for a song; it composes, listens, and revises while you hear every change in the studio. See working with an assistant.
• The command line. claudius make --genre lofi writes a finished song to a folder. See command line.

Where to start

• You have never made music. Install it, make your first song, then follow how a track is built. The chapters explain every term as it comes up and give you something to listen to on every page.
• You make music already. Read claudius for DAW users and keep the quick reference open. If you know Strudel or TidalCycles, start with coming from Strudel.
• You want to work on claudius. Start with a tour of the repository and the architecture.