JJazzLab 4

A complete and open application for backing tracks generation.

Want to add or fix documentation? Yes you can!😀 Visit the Improve documentation page.

Where to start?

Try this very short video tutorial or the Editors overview page.

What is JJazzLab?

🎵 JJazzLab is a desktop application which automatically generates backing tracks for any song, even complex ones. It’s a jam buddy to have fun improvising at home, learn new stuff or just practice your instrument. It’s also a great tool for teachers.

🎷 JJazzLab is designed to make non-boring backing tracks, backing tracks with variety, rhythmic accents and dynamics. You can start a solo slowly and gradually build up the atmosphere!

💻 JJazzLab is open-source: developers can easily add new features and new music generation capabilities.


Backing tracks

  • Instant generation of a Midi backing track with drums, percussion, bass, piano, guitar, pad, horn section, …

  • Fine tuning of the backing track per song part: rhythm variation, intensity, muted instruments, drum fills, tempo factor, custom phrases, drums transform, …

  • Add user tracks, which can also be used to change predefined rhythm tracks

  • Play from anywhere, loop selected bars

  • Play transposed (e.g. for sax or trumpet players)

  • Any song structure: intro, chorus, 1st coda, etc.

  • Adjust tempo, transposition, choose and solo/mute instruments

  • Support for multi-rhythm backing tracks, possibly with different time signatures

  • Export to Midi or MP3/Wav file, the full backing track or a single instrument track

  • Customizable click and pre-count


  • Chord lead sheet editor, song structure editor, chord symbol editor, mix console, notes editor, song memo editor

  • Multi-file editor with dockable windows

  • Intuitive user interface with unlimited undo/redo, copy/paste between songs

  • Free placement of the chord symbols (quantified or not), off-beat chord symbols anticipation

  • Support all pop-rock and jazz chord symbols, plus user-defined chord symbols

  • Edit chord symbol musical rendering: underlying harmony, accent type, harmony variation during solos, chord symbol substitution, …

  • Add annotations or lyrics to measures

  • Drag & drop support to import/export Midi files

  • Customizable song template

  • Customizable colors and fonts

  • Print chord lead sheet and song structure

Rhythms (styles)

  • Support for Yamaha style files (SFF1 & SFF2 format), access to thousands of free styles on the web

  • Hundreds of embedded rhythms in the installer

  • Support for “YamJJazz Extended Yamaha" style files for even more variations per style

  • Open architecture: new rhythm generation engines can be easily added via plugins

Easy reader window

  • Show the currently playing chords and annotations/lyrics

Notes viewer

  • Show selected chord symbol notes and scales with piano keyboard, guitar diagrams or score

(pseudo) Arranger keyboard mode

  • Recognize chords played on Midi IN and update the backing track in (pseudo) real-time

Improvisation help

  • Automatic generate improvisation guides on your chord leadsheet

  • Based on Hal Crook's reference book "How to improvise"

FluidSynth, the JJazzLab builtin synth

  • JJazzLab embeds a ready-to-use synth based on FluidSynth, with good sounds optimized for JJazzLab


  • If not using FluidSynth, you still can connect JJazzLab to a Midi synth (hardware or software) with advanced configuration possibilities


  • Band-In-A-Box / MusicXML / Impro-Visor lead sheet files

  • Import .txt files or copy/paste text like "|A7 D7 | Gm7 C7|"


  • Song memo with hyperlinks opened upon song loading

  • Easily add new features thanks to the open-source pluggable architecture

  • Based on the Netbeans application framework

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