A browser MIDI instrument for loops and songs
Soundfish
Make music in your browser, turn loops into a song, and share the complete composition in one playable link. No account needed.
Ask your agent to add a bass track under the drums, leave the melody as it is, and hand back the new link.
No account. $0 as of September 5, 2026, recorded on the pricing page. A Bun CLI is available as @hraness/soundfish.
Source https://sound.fish/ · 10.4 seconds · 1280 × 720 H.264 · no private data recorded · Inspect the capture manifest
How it works
Composing, playing, sharing, and agent editing are separate jobs. The URL is what passes between them, and you can inspect it at every step.
Open a musical starter or import MIDI, JSON, or a loop link. Place notes and drum hits, shape the mix, and turn variations into a song with Arrange sections.
Press Play to hear your instruments and mix. The first use of an instrument may need a download; nothing plays automatically.
Choose Copy link to share the complete composition in one playable URL. In More, download Soundfish JSON to keep an exact copy, or Standard MIDI to work in other music software. Song downloads contain the whole arrangement.
Choose Edit with agent and describe the change. Chat agents return loop text; coding agents use the CLI for exact loop or song edits. Review the reply before opening a new playable link.
Interfaces
The browser and the CLI act on the same document without pretending to be the same tool.
Make music in the browser. Edit, play, mix, and keep loops in the browser. Library keeps loops and saved songs on this device. Optional sign-in syncs loops across devices; complete links and Soundfish JSON keep either composition portable.
A musical request and a reviewed reply. Choose Chat app for a loop draft without an install, or Coding agent for exact edits with the Soundfish skill and CLI. Copy the prompt, send it to your agent, and review the reply in Soundfish.
Commands for loops and songs. Run bunx @hraness/soundfish once, or install the soundfish command. Inspect and verify loops or songs, export either as JSON or MIDI, and orchestrate authorized local song imports through StemDeck and Basic Pitch.
Protocol evidence
The canonical protocol says exactly what addresses the music, what protects transport, and what determines sound.
An editable loop travels as #s1.<music-cid>.<codec>.<payload>.<transport-digest>. Inspect the canonical URL protocol
Trust boundary
Soundfish keeps ordinary composition work client-side, then names every feature that crosses that boundary.
Read the complete privacy disclosure
Questions
No. Open, edit, play, save locally, and share without signing in. Sign-in is optional and syncs loops across devices. Saved songs stay on this device.
The hosted editor currently costs $0 and has no published paid plan or purchase flow. That current price is not a promise about future features or service levels.
It is client-side during ordinary navigation, not confidential. Anyone with the complete URL can decode the composition, and a hosted agent receives it when you paste the handoff.
No. The published CLI runs on a complete editable-loop Soundfish URL or local .soundfish text and returns another verified loop URL. It also inspects, verifies, and exports read-only songs. Soundfish exposes no unauthenticated hosted mutation endpoint for canonical documents.
Use Download Soundfish JSON for the complete loop or song model and Download MIDI for other music software. Song MIDI carries tempo, tracks, programs, notes, velocities, duration, and section markers; JSON or the complete URL retains effects, automation, identities, lineage, and arrangement routing.
Yes, from authorized media. The local soundfish song import command orchestrates separately installed StemDeck and Basic Pitch tools and writes reviewable loop and song artifacts. Separation, analysis, and transcription are estimates, so audition and correct the result.
A loop or track rename changes its payload and transport digest but not MusicCID. A song or section rename likewise changes its payload and transport digest but not ArrangementCID, because titles are transport metadata rather than authored musical meaning.
Built by
Soundfish is made by Ben Guo, a musician and builder. He was a founder and an engineering leader at companies including Venmo and Stripe, and he now builds from Puerto Rico.
No account, upload, or setup is required for the first loop. $0 as of September 5, 2026.