Runphony - Every run hides a song. Runphony composes it.

Hi Product Hunt, I kept finishing runs, looking at a chart of my pace, and thinking that a run has an obvious shape to it — a warm-up, a build, a hard middle, a sprint, a cool-down — and that's the shape a piece of music has too. So I built the thing that maps one onto the other. Runphony takes a workout you have already recorded — Health Connect, Apple Health, or a GPX/TCX file exported from Strava, Garmin, anything — and composes an original instrumental track from it. Nothing to record, no live tracking, no accelerometer running in your pocket. What actually drives the music: • Cadence sets the tempo. 170 steps per minute becomes 170 BPM, so your own footfalls land on the beat. • The phases of the run become the sections of the song. Warm-up, steady, push, sprint and cool-down each get a distinct musical role, so the track has a beginning, a build, a peak and a resolution instead of one flat loop. • Effort controls the arrangement — more layers where you worked hardest, sparser where you eased off. • Heart rate, when you have it, shapes the key and the mood. It deliberately does not touch tempo: heart rate lags effort, it keeps climbing after a sprint has ended. • The shape of your route shapes the song's structure. A loop comes home to where it started; an out-and-back mirrors itself on the way back. Two things I want to be upfront about, because they're the questions I'd ask: It is not a generative AI model. There is no cloud call, no prompt, no credits. It is a composition engine and a SoundFont sampler running entirely on your phone, and it is fully deterministic — the same run always produces the same track, so a run you liked is never lost. That constraint is the whole reason it stays tied to your effort instead of to a genre prompt. And the output is instrumental. No vocals, no lyrics. If you're arriving expecting something Suno-shaped, this is a different thing. You can export the finished track as a short video built from your own run — your route, your phase timeline, your stats — animated in one of six visual styles (cassette tape, retro handheld console, comic panel, cosmic orrery, scrapbook, neon pulse). That part exists because a song you can't show anyone is a song you forget about. Free gives you a preview of every track, one music style, and watermarked video export. Premium unlocks full-length tracks, all nine music styles, all export styles without the watermark, themes, unlimited history and cloud backup. Health data is read-only, never written, never sold, and there are no ads, no analytics and no tracking of any kind. Heart rate and route access are both optional — it works without either. Happy to answer anything, especially about the mapping. That's the part I spent the most time on and the part I'd most like to argue about.