Version 26.8u
© 2026 JDS Software
Twenty backing styles across the genres, from waltz and folk to trance and lo-fi. Choosing one and pressing Set the band arranges everything except your melody: the drum kit and pattern, the bass and pad sounds, the arpeggio shape, the tempo, swing, time signature, chord progression and the feel of each part. Your Lead, its instrument and every note you have written stay exactly as they are. The band plays from then on, worked out from the key and progression; Clear the band takes those parts away again and leaves everything you drew, filled or imported untouched.
Every pattern is generated by this app from its own settings, nothing is recorded, sampled or copied from any published music, so all of it is original, royalty free, and yours to use in anything.
Analyse and master renders the piece, measures what is actually there, and sets the equaliser and level to suit. It is measurement rather than a preset: the piece is played through a filter for each band and the real energy in each is compared with where a finished mix usually sits, so two different tunes get two different settings.
Master tone is the character you are after. Warm favours the low end and eases the top; Balanced aims at an even, natural spread; Open clears the lower middle and lifts the air so the piece sounds wider and brighter.
Playing on matters more than people expect. A phone or laptop speaker cannot reproduce the bottom octaves at all, so energy down there is wasted and can make the speaker distort; that setting trims it and lifts the presence range instead, which is what carries a tune on a small speaker. Headphones need less presence and keep more of the low end. Full range leaves the balance alone.
Loudness for is what matters most if you are publishing. Streaming services do not play your file at the level you made it: they measure its loudness and turn it down to their own, so a track squashed to be louder than the target gains nothing and simply arrives squashed. Streaming and YouTube sit near -14 LUFS, Apple Music nearer -16, club and DJ use much louder at -9, broadcast quieter at -23. Pick where the track is going and it aims there, and it will not crush the peaks to reach it.
How thoroughly trades time for accuracy. Quick stops after the opening twenty seconds or so, which is enough to judge the balance of most pieces and takes a fraction of the time on a long one. Full renders the whole piece at a higher rate, so it hears every section and measures the top end more finely; use it when a piece changes character part way through, or before you export something you care about.
It measures the piece with the equaliser flat, so the result does not depend on what the sliders happened to be set to, and running it twice gives the same answer. Undo master puts the previous settings back.
What this is not: proper mastering services use models trained on large catalogues and do multiband compression, stereo work and limiting. This does honest corrective equalisation and level setting from a real measurement of your piece. It will get a tune sounding consistent across speakers; it is not a substitute for a mastering engineer on something you are releasing.
Digital synthesis is unnaturally perfect. Every note is a bit-for-bit copy of the last one, every waveform starts at the same point in its cycle, drum hits are identical bar after bar, and the silence is absolutely silent. No instrument, player or recording behaves that way.
Switching this on puts the imperfections back. Each note gets its own tuning drift and settles into pitch the way a real one does, waveforms start at a random point so repeats never line up, the tone colour shifts slightly note to note, every drum hit lands a little differently, the whole mix passes through gentle valve-style saturation, the instruments sit in a small generated room, and a faint noise floor sits underneath, as one would from any recording chain.
It also reshapes the sound itself. Notes begin with the noise of being started, the breath, bow, hammer or pick that any real instrument makes before it speaks. They grow duller as they fade, because on a real instrument the high partials die first. Extra partials sit slightly sharp of the exact harmonics, the way a stiff string genuinely behaves rather than the perfect whole-number ratios an oscillator produces. Each part is placed a little differently across the stereo picture. And every instrument is given a body: a fixed set of resonances that colour each note the same way wherever it sits, instead of the whole spectrum sliding up and down with the pitch as a synthesiser’s does.
It applies to playback and to every export, so what you save is what you heard. The variation is worked out from each note’s place in the piece rather than rolled fresh each time, so a piece plays and exports as one fixed performance: the preview, the WAV, the MP3, the stems and the MIDI all agree, and two saves of the same piece match each other. Recompose or a new Variation gives you a fresh take whenever you want one.
Worth being straight about: this is a genuine improvement to how the music sounds, not a trick. It may well change how an automatic checker classifies your track, since those tools largely react to exactly this sort of machine-perfect spectral and timing evidence, but nobody can promise a particular verdict: the checkers are closed and they change. If you are ever asked how the music was made, the accurate answer is the honest one: composed and synthesised by this app from your own notes and settings, with no generative AI model involved.
Presets are kept by this browser on this device. Mark one as Default and it loads automatically.
Import MIDI reads a .mid file and lays its notes on the lane you have selected in Tracks (or the Lead if none), so you can drag, draw and edit them like any other notes. Drum channel notes land on the drum lane. It offers the file’s own tempo, and lengthens the piece if the file needs more bars.
Import audio brings in a WAV, MP3, or any other format your browser can decode, and places it as a clip on the selected lane at the current play position. Audio clips play alongside the notes, follow that lane’s level, mute and solo, and are included in WAV, MP3 and stem exports.
Select bars on a lane and use Crop, Split, Remove, Copy audio and Paste audio to trim clips and move parts between lanes.
One limitation: audio is held in memory for this session only. It is far too large to store in a project file or the autosave, so imported audio is not saved with the project. Export to WAV or MP3 to keep the mix.
Enhance makes automated musical corrections, in the spirit of autotune, to the notes of the selected lane or the whole piece. Tune to the key pulls every note onto the current scale. Lock to the chords also lands notes falling on the beat onto that bar’s chord. Smooth the leaps folds awkward jumps of more than a fifth into the nearest octave. Tighten the timing nudges drawn and imported notes onto the half-beat grid.
It works on drawn notes, imported MIDI, and the composed melody (kept as stored corrections, so Undo brings the old notes back). One honest note: imported audio recordings are finished sound rather than notes, so they are not pitch-processed.
Cut splices the selected bars out of that track; Restore brings them back. Fades shape the amber level line across the selection. Everything here plays and exports exactly as shown.
| Track | Voice | Sound | Pace | Ring | Loop | Level | Feel (humanise) | Tune |
|---|
Two kinds of instrument file are supported.
SoundFont (.sf2) is the industry-standard sampled-instrument format used across most music software. Its instruments load into the Lead list marked with a ♪ and play from real recorded samples. Big banks load the first eight instruments.
One limitation: to stay a single offline file, each SoundFont instrument plays one representative sample stretched across the whole keyboard, rather than a full multi-sample synth with a different recording per key. It sounds natural across a normal melodic range, but very high or low notes will sound more stretched than in dedicated sampler software.
JDS patch (.json) is this app's own lightweight synth format, marked *, describing oscillators and an envelope. See example-instruments.json.
Both travel inside a saved project, so opening it elsewhere brings the instruments too. VST and AU plugins are not supported, as they cannot run in a browser.
A short guided tour walks through every section, one control at a time. It takes a few minutes and you can stop at any point.
You can start it again whenever you like from the menu, under the app icon at the top left.