Jam-a-Lot
Join the Free Beta
Jam-a-Lot generates a real-time rhythm section — walking bass, comping piano, and a feel-aware drummer — over 1,382 open-source standards. It hears you through your mic, follows your dynamics and phrasing, and drives your practice session with zero installs or sample downloads.
The Beta is free and always will be during beta — the whole app, in exchange for telling us what's working and what isn't. No card, no trial clock. Prefer to look around first? Guest mode plays 3 demo tunes with the full band, no sign-up.
No robotic quantized MIDI, no rigid pre-recorded stems, no 90s software bloat. Jam-a-Lot gives you an interactive, humanized rhythm section in your browser, including section-level Salsa bell drive for slow-tempo flexibility.
Jam-a-Lot subtracts its own speaker sound from your mic per frequency bin, then adapts the band's intensity, phrasing, and voicings to your solo.
Play softer and the band comes down; build and the band builds with you. Integrated frequency-selective speaker leakage suppression lets you play through room speakers.
Leave a gap at phrase ends and the band responds. Piano comping voicings shift register to match your pitch height and comping density.
Repeat a rhythmic figure twice and the drummer locks on, playing it with you through the section and resolving it cleanly into the section fill.
Section boundaries are announced with hand-off fills and downbeat crashes. Chorus arrivals are clearly stated so you never lose your place in the form.
Jam-a-Lot aggregates open-source chord collections — a 1,382-tune jazz-standards corpus, academic chord datasets, community lead-sheet archives, and public-domain imports. Search once, play immediately.
1,382 jazz standards — bebop, modal, swing, ballads, bossa, latin, waltz, and songbook classics.
Open academic chord datasets — practice over familiar progressions and popular tunes.
Public-domain lead sheets import straight in, with full MusicXML and text chart support.
Paste a text chart with repeat and Coda directions, plus separate forms for solos and the last head. Your saved text keeps its section order and spacing, and written intros and endings play as one-shot sections. Edit bar by bar with beat-accurate punch figures, or fork any catalog standard into a personal custom version.
Send charts to @handles, share via QR codes or links, and auto-sync your library across all devices.
Generated on the fly bar by bar — giving you real-time control over chorus dynamics, trading, feel switches, and reharmonization while you play.
Shape the next chorus without stopping. Double time into the out-head, drop to half-time for the bass solo, or dial drummer intensity (1–5) at phrase boundaries.
Press trade to exchange fours, eights, or full choruses. The drummer solos with comping behind you and hands off with phrase-locked cymbal splashes.
Phrase-planned Coltrane cycles, Bird Blues, turnaround and bridge families, tritone ii-Vs, secondary dominants, and back-door turns — all without mutating stored charts.
Switch feels mid-performance, transpose ±1 semitone instantly, or loop sections until clean. Computed from absolute beat clocks with zero timing drift.
Everything you need to woodshed a standard in one clean browser tab.
In-place editing with root × quality × extension pickers, text mode, stable numbered-ending routes, reharm suggestions, and a roadmap strip.
Seeded walking bass, phrase-aware comping piano, and feel-aware drums that groove deterministically without fixed loops—including eight-bar Bolero piano statements that develop across the chorus.
Decibel faders, voice mutes, and per-instrument stereo panning that places each musician across the virtual stage.
Acoustic jazz kit, Latin percussion, and a groovebox synth. Tresillo layers kit drums with hand percussion. Build and audition custom accompaniment styles in the lab.
Generated bass lines render on readable staff notation. Review after Stop, print, or export directly to MusicXML.
In-app wiki covering rhythm style structures, plus integrated Spotify and YouTube reference embeds for context.
Zero install, zero sample downloads. Open a tab and start playing.
3 demo tunes open instantly; 1,379 more unlock with a free Beta account. Color-coded chart renders instantly.
Choose a rhythm style, dial tempo, transpose keys, set per-chorus performance plans, and practice ii–V–I cadences, turnarounds, dominant cycles, or Coltrane changes through fixed or random key steps.
Count in and jam. Adjust chorus dynamics, trade fours, or turn on mic listening live while you play.
Yes! During open Beta, the complete app is 100% free in exchange for your feedback. There is no credit card required and no trial timer. Guest mode lets you test 3 tunes with zero sign-up.
No. Jam-a-Lot is completely browser-native. There are no desktop installers and zero multi-gigabyte sample packs to download. It runs smoothly on any modern desktop or tablet browser.
Both work! Jam-a-Lot includes frequency-selective band leakage suppression that subtracts the backing band from your mic input in real time. You can play through room speakers or headphones seamlessly.
Yes. You can edit chord symbols with live validation, paste plain-text lead sheets, sketch original compositions, and export your generated bass lines and chord charts to MusicXML or neutral JSON formats.
Jam-a-Lot is in open beta with nothing to pay. All we ask in return is your honest feedback to help us improve the band. Prefer to try it first? Guest mode plays 3 demo tunes with the full band, no sign-up.
Hear the band before you decide anything.
The entire app. All we ask for in return is your honest feedback.
Sign up with Google or an email address in fifteen seconds. Jam-a-Lot stores only chord symbols and song form; never melody, never lyrics, never proprietary formats.
Pick a tune. Shape the band. Play. Then tell us how it went.