Run to your beat.
Green Onions stretches the music you already own to match your running cadence — in real time, without changing the pitch. Your songs, at your tempo. Nothing sounds like a chipmunk.
Coming soon to iPhoneThe idea
Every running app makes you run to their playlist. This one runs to yours.
Tempo-matching apps hand you a catalog and a subscription. Playlist apps just sort songs into BPM buckets and hope something fits. Green Onions does the harder thing: it analyzes the tracks already on your phone and time-stretches them to your exact cadence as you run — so a song at 148 BPM becomes a song at 165 BPM, still in key, still sounding like itself.
What you get
Plays the files and iTunes purchases already on your phone. No catalog to browse, no licensing gaps, no "this song isn't available."
Real-time time-stretching that holds the original key. Songs speed up to your cadence without turning into chipmunks.
Nudge your target tempo up or down mid-run without unlocking your phone or breaking stride.
Fully offline. No signal, no problem — trails, tunnels, treadmills, airplane mode. Everything runs on the device.
No sign-up, no subscription, no ads. You don't make an account because there's nothing to make an account for.
No analytics, no telemetry, no profile. Your library and your runs stay on your phone.
What surprised me
I never thought I'd be able to run to Neil Young.
— Brian, building this thing
That's the part I didn't expect. When any song can meet your cadence, "running music" stops being a genre you tolerate and starts being the music you actually love. Records that were never remotely workout material turn out to be perfect — they just needed to arrive at the right tempo.
Mid-run
You're in the home stretch and you want to push. Reach down, tap + right on the lock screen, and the music comes with you — the tempo climbs to the pace you're about to run. No unlocking, no fumbling, no stopping.
Live Activity controls on the lock screen and Dynamic Island.
Illustration of the lock-screen controls
Who it's for
Hold a steady cadence instead of drifting with whatever song shuffles up. Dial in a target, nudge it as you go, and let the music do the metronome work. Cadence is a rhythm you can hold at any pace — that's exactly why matching it works.
Steady rounds at a moderate tempo, or speed work up top. Set the beat, keep the rhythm, stop counting in your head.