About TempoFlow

TempoFlow is a free, browser-based tool for analyzing music. Drop in any MP3 and the site detects the song's BPM, beat offset, and tempo changes, then lets you fine-tune the result in a visual editor and export a JSON file describing the beat layout.

What it's for

The tool was originally built for rhythm-game players who want to play along to their own music collection rather than the bundled tracks. Once rhythm-game players had a working detector, the same workflow turned out to be useful for:

• DJs cuing into unfamiliar tracks.
• Producers verifying the BPM of unmastered demos.
• Choreographers and dancers preparing routines.
• Music students transcribing songs by ear.
• Video editors needing a click track aligned to an existing song.

How it works

The detector chains a multi-feature beat tracker with a sliding-window inter-beat-interval analysis. The first stage produces a confident global tempo and a list of beat timestamps; the second stage scans those beats for sustained tempo changes (avoiding flicker by requiring multiple consecutive windows to agree) and snaps each change point to the nearest detected beat. The output is a clean list of tempo sections that match the song's structure rather than the noise floor of the analysis.

Privacy

TempoFlow doesn't have user accounts. Audio you upload is processed once and discarded — there's no storage of files, no logging of what you analyzed, and no third-party trackers on the analysis flow. See the privacy policy for full details.

Contact

Bug reports, feature ideas, and tracks the algorithm fails on are all welcome. Use the contact page.