3.9 / 5

AI Accompanist

Play melody on your keyboard, AI plays chords and bass in real-time

Serious

Real-time

Zero Cost

The Problem

Solo practice lacks the feel of playing with others; backing tracks don't respond to you

Current Solutions (Not Great)

Backing tracks (non-responsive), Band-in-a-Box ($400+), finding jam partners (scheduling)

Who Needs This

Piano/keyboard players, music students, hobbyist musicians, singer-songwriters

Playing piano alone means playing everything yourself—melody, chords, bass. AI Accompanist listens to your melody and plays tasteful accompaniment underneath: chord voicings that fit your notes, bass lines that provide foundation, rhythmic patterns that match your feel. It's like having a rhythm section that follows you perfectly. The 50ms latency buffer means you hear everything in sync—your melody and the AI response feel simultaneous. Practice feels like performing with a band, and suddenly that simple melody sounds like a full arrangement.

Honest Take

Band-in-a-Box has owned this space for decades at $400+, so there's proven demand, but making AI accompaniment sound musical (not robotic) is the real challenge. The browser-native angle and lower price point could work, though you're competing with established tools that already have extensive style libraries.

Monetization Ideas

Ways to turn this into revenue

Freemium

Free basic, $5-15/mo for pro

Subscription

$5-29/month or $49-199/year

One-Time Purchase

$9-49 per license

Features

Key features that make this app valuable

Real-time chord detection from melody
Tasteful chord voicings (not just root position)
Bass line generation
Style presets (jazz, pop, ballad, bossa nova)
Dynamics following (play soft, it plays soft)
Key/scale awareness
Adjustable complexity
Multiple instrument sounds

Build Prompt

Use this prompt with an AI assistant to start building

Build a React PWA called 'AI Accompanist' using WebInfer and Web MIDI API. Core architecture: request MIDI access, listen for note events. Create AudioContext with Web Audio API. Implement latency buffer: when note received, schedule playback at audioContext.currentTime + 0.05 (50ms). Simultaneously, add note to analysis buffer (rolling window of last 2-4 beats). AI analysis runs on each note: generateObject returns { key: string, scale: string, currentChord: string, nextChord: string, bassNote: number, voicing: number[], rhythmPattern: string, intensity: number }. Schedule AI notes at same time as user notes. Synth engine: use OscillatorNode or sampled instruments for piano, bass, pads. UI: MIDI device selector, style dropdown (Jazz Trio, Pop Band, Ballad, Latin, Singer-Songwriter), intensity meter, key display, chord chart showing detected/predicted chords. Visual keyboard showing user notes (blue) and AI accompaniment (green). Record button captures session as MIDI file. Settings: accompaniment instruments, voicing complexity, bass pattern style.

Score Breakdown

Pain