Free · No account · Works offline
JamShed is a jazz trio — double bass, drums and piano — that plays any of 123 standards or your own chords with you, at the tempo and in the key you choose. Nothing is a recording: every time you press play the trio composes its accompaniment inside the form, grows through the solos and comes back down for the head, the way records do. In the browser, or installed on your computer and your phone.
Bars are separated by | · two chords in a bar: Dm7 G7 · % repeats the previous bar · it reads Dm7 D-7 Cmaj7 C^7 Bø G7alt F#m7b5 D/C…
Roman numerals, function and ii–V–I, chorus by chorus.
Separate MIDI tracks for your software, or the trio as audio.
React Trio beta
A backing track that listens. Through the microphone, the trio follows your dynamics, gives you space when you get busy and lifts when you rest — one bar later, like a real rhythm section.
| Bar | Level | Notes | Rest | Intensity | Trio |
|---|
Tap a bar to practise from there; tap another to set where it ends. Tap the first one again for the whole form.
New in JamShed · Beta · Practice Pass
The backing track that listens to you.
Every backing track plays the same whether you are there or not. A real trio doesn’t: it hears where the soloist is going and goes with them. React Trio brings that to practice. Turn it on, let the browser use the microphone, and the bass, drums and piano react to how you play — one bar later, never in the middle of your phrase.
The first time you press play, the trio plays two bars on its own while you wait. JamShed learns how loud the trio sounds in your room and how late its echo reaches the microphone — so it can tell you apart from the speakers. That is why you don’t need headphones.
While you play, an audio processor in the browser subtracts the trio’s echo and measures what is left: how loud you are, how many notes you play and how much space you leave. Your level is read against your own range, so a quiet player and a loud one get the same response.
At the end of each bar it decides how the trio plays the next one. The lines are still the ones JamShed composed from your chords; what changes is the touch — how hard, how much, and where. What keeps time — ride, hi-hat — is never moved.
Play louder and the piano digs in, the snare and kick come up, the bass leans in with you.
Bring it down and the whole trio comes down with you, so a quiet chorus stays quiet.
Long lines of eighth notes and the piano thins out, leaving off-beat hits out of your way.
Stop for a bar and the trio picks up a little, like a band when the soloist breathes; the piano strikes its chord again on the “and” of three.
The app · Free · Works offline
One tap and JamShed lives on your computer or phone, with its own icon and its own window. The player, the sounds, the 123 tunes and the 129 analysed standards stay on the device, so it works in a practice room with no signal. It updates itself whenever the site does.
✓ You are in JamShed. Everything here works offline.
On a computer: Chrome or Edge show Install in the address bar.
Nothing here is a recording. Each time you press play, the accompaniment is composed from your chords: the double bass walks with chord tones and chromatic approaches into the next bar, the drummer swings on the ride with the hi-hat on two and four, and the piano comps like a trio pianist — rootless voicings, anticipations, space, and dynamics that move in phrases.
On long modal chords — So What, Impressions, Milestones — the piano stops repeating one shape: it moves through the mode in fourths, comes home every four bars, and now and then side-slips a half step and resolves. On a chord that lasts two or three bars it changes inversion instead of hammering the same voicing.
Slow the tempo down until the hard bars are easy, then raise it a few clicks a day. Tap the two or three bars that keep tripping you and loop just those. Move the tune to another key to stop playing it by finger memory. Mute the piano if you are the one comping, or the bass if you want to walk the line yourself.
The link carries the whole track — chords, tempo, key and the take — so a teacher can send a student exactly what to practise over, free. Save keeps your own progressions to open them again, and Export gives you the track as MIDI — bass, piano and drums on separate tracks for your recording software — or as MP3 or WAV audio: both are part of the Practice Pass.
Swing walks in four (or two-feel), in 4/4, as a jazz waltz in 3/4, or in 5/4. Ballad is slow swing: bass in two, a soft ride with no bass drum, long chords on the piano. Bossa nova puts the bass on root and fifth with the anticipated eighth, a cross-stick on the bossa clave and straight eighths on the hi-hat. Latin plays a tumbao — the bass lands on the next chord a beat early — with cascara on the ride bell, 2-3 clave and congas. Even 8ths is the straight groove of tunes like Watermelon Man or Cantaloupe Island. Each standard opens in its own style; you can change it.
On an iPhone, turn the silent switch off: it mutes web audio.
