JJazzLab

What it does

Enter a chord chart, pick a style, and it builds a full backing track — drums, bass, guitar, piano, strings — deliberately shaped with variation and dynamics rather than looping the same bar. A customised FluidSynth engine is built in so it makes sound on its own, and you can route it to VST instruments over a virtual MIDI cable for better tone. Free installers for Windows, macOS and Linux; the UI is community-translated into several languages. Rule-based rather than generative AI, which makes the output predictable and easy to steer. LGPL-2.1.

Summary based on the project's own description. The Japanese page has a fuller beginner guide: setup difficulty, what to prepare, and a step-by-step start.

Screenshots & visuals

Before you start

• Setup difficultySome setup needed
• Command lineNot required
• API keyNot required
• Sends data onlineNo

Judged automatically from the project's own metadata. Always confirm on the official page.

JJazzLab FAQ

Is JJazzLab free?

Yes. It runs on your own machine, so there is no usage-based cost either.

Do I need to install anything or write code to use JJazzLab?

You install it like a normal desktop app. No command line involved.

Does JJazzLab work on a phone?

No. It needs a computer.

Can I use JJazzLab commercially?

The licence is LGPL-2.1. Using it commercially is fine, but if you distribute something built on it you may be required to release that under the same licence. Keep it internal, or check before distributing.

How it compares

The conditions that decide whether you can actually use it, side by side.

"Sends data out" means your input is uploaded to someone's server. Pick "No" when the material cannot leave your organisation.

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