Groove Number
swing %, bpm, key, on-device
$1.99 · Designed for iPad. Not verified for macOS.
point it at a track and get the groove number: swing %, bpm, key, four ways to see the beat. record, then take your groove to a daw as midi. on-device, no upload.
how swung is your track? groove number gives you the number.
drop in a song, record a clip, or open the live mic — groove number listens and tells you the one thing drum machines flatten and great players bend: the groove. 50% is dead straight. ~66% is full triplet swing. most music that feels good lives in between, around 54–62%. now you can see it.
and it's not just the number.
what it reads
• swing % — the hero. one honest number for how far off the straight grid the groove sits.
• bpm — dual-estimator with an octave guard, so 174 never gets called 87. nudge it ×2 / ÷2 or tap the tempo to lock it, and the swing recomputes against the corrected grid.
• key — chroma + krumhansl-schmuckler with a tuning estimate, shown with a confidence read and the runner-up key, so a close call never hides.
four ways to see it
• meter — the number, front and center: swing %, bpm, and key in one calm readout.
• swing grid — the signature view. every onset plotted against the straight 8th/16th grid, colored on-time, late, or rushing. you can see the pocket.
• spectrogram — mel-scaled heatmap, quiet to loud, low to high, with a frequency + dB scale.
• chromagram — the 12 pitch classes over time, tonic marked.
how it listens
• a file you drop in or pick (mp3, m4a, aac, wav, aiff, flac)
• a clip you record — it listens and stops on its own the moment the groove locks
• the live mic — a running bpm + swing read in the room, with a VU level meter and a live spectrogram
one more thing
• groove → midi — export the groove as a midi clip, swing baked into the note timing. drop it on a drum track in any daw and it plays your pocket.
built to be calm and honest
• fully on-device. your audio is analyzed right on your iphone, ipad, or mac. nothing is uploaded. nothing is stored on a server.
• no account. no sign-up. no ads. no tracking.
• strongest on four-on-the-floor and electronic music. live, acoustic, and rubato material is harder — so groove number always shows its confidence and hands you the ×2/÷2 and tap-tempo overrides. wrong calls stay visible, never silent.
one number for the feel of a track. plus everything you need to trust it.
Ratings & Reviews
a few fixes, and a smoother feel throughout.
- live no longer comes up silent the first time you start listening right after loading a file.
- record only hands over a take once it has actually found a groove in it, instead of stopping at a flat eight seconds with nothing to show.
- adjusting the tempo (tap, ±1, ×2, ÷2) now updates the midi export too. it used to keep the old bpm.
- the whole app eases in instead of snapping: the vu needle, adjust tempo, the record pulse, live's readouts.
- analyze shows when it's still listening for a song id, instead of going quiet for a few seconds.
same on-device analysis. no account, no upload.
The developer, Joshua Langberg, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Collected
The developer does not collect any data from this app.
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
For more information, visit the developer’s accessibility website .
Information
- Seller
- Joshua Langberg
- Size
- 2.7 MB
- Category
- Music
- Compatibility
Requires iOS 17.0 or later.
- iPhone
Requires iOS 17.0 or later. - iPad
Requires iPadOS 17.0 or later. - Mac
Requires macOS 14.0 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 1.0 or later.
- iPhone
- Languages
- English
- Age Rating
4+
- 4+
- Copyright
- © Joshua Langberg 2026

