About Chord Progressions

What it is

Chord Progressions is a free web app that generates a live jazz backing track - piano, bass, and drums - from any chord chart you give it. Load a standard from the built-in library of ~1,000 tunes, paste your own changes, or drop in a MusicXML file. Set your tempo and feel, hit Play, and practice over a full rhythm section instantly.

Everything runs in your browser using the Web Audio API. There are no plugins to install, no downloads, no account to create, and no audio streamed from a server. It works on laptops, tablets, and phones, and continues working offline once it has loaded once.

Why it was built

Most musicians practice alone. When you're working through a new standard, transcribing a solo, or learning to improvise, you often want a rhythm section behind you - but setting one up takes time: loading a DAW, finding a backing track at the right tempo, dealing with a track that's in the wrong key.

Chord Progressions exists to make that zero friction. You type the changes, pick a tempo, and you're playing. The entire point of the tool is to get out of the way as fast as possible so you can focus on music.

What makes it different

• Chord-driven, not track-based - the accompaniment is generated in real time from your chart, not a pre-recorded audio file. Change a chord, and the band changes with it immediately.
• Built for jazz - the instrument voices, playing styles, drum feels, and the built-in library are all curated for jazz practice specifically. It handles standard jazz chord symbols out of the box.
• Mixer control - balance piano, bass, drums, and metronome independently. Mute instruments, set trade bars, choose drum feel, and configure loops without leaving the player.
• Genuinely free - no ads, no freemium, no subscription. The app has been free since it launched and that is not expected to change.

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Technology

The app is built with TypeScript, React, and the Web Audio API. Audio playback uses sampled instruments processed locally by the browser's audio engine. The chord parser handles hundreds of common jazz symbols including extensions, alterations, omissions, and slash chords.

The app is a Progressive Web App (PWA), which means you can install it to your home screen on iOS, Android, or desktop and use it offline exactly like a native app.

Contact

Found a bug, have a feature request, or want to contribute charts to the library? Reach out at hello@chord-progressions.com .