TempoFlow

Find every beat of your music

TempoFlow analyzes any music track and detects BPM, beat offset, and tempo changes with section-level precision. Fine-tune visually, then download a ready-to-use JSON configuration for your rhythm workflow.

Upload Your Music

Drag & drop your MP3 file here

or click to browse

How to Use

  1. 1
    Upload

    Drop your MP3 file into the upload area above. Files are processed and discarded after the response — nothing is stored.

  2. 2
    Analyze

    A multi-feature beat tracker estimates the global BPM, then a sliding window scans for sustained tempo changes and snaps each change point to the nearest detected beat.

  3. 3
    Fine-tune

    Verify the beat lines on the waveform, drag section boundaries, edit BPM directly, or use the metronome click to align by ear.

  4. 4
    Export

    Download a JSON file containing tempo, offset, and a list of tempo sections. Drop it into the appropriate folder for your target tool.

FAQ

What does TempoFlow do?

TempoFlow is a free online BPM detector and tempo change analyzer. Upload an audio file (MP3) and the tool estimates the song's tempo, the beat offset (where the first beat lands), and any tempo changes inside the song. You can then fine-tune everything by hand and export a JSON file describing the beat layout.

How accurate is the BPM detection?

The analyzer uses a multi-feature beat tracker (drum onsets, spectral flux, low-frequency energy) to handle electronic, rock, pop, and acoustic material. For most songs the global BPM is accurate within ±0.5. For tracks with rubato, ritardando, or sudden tempo shifts the algorithm splits the song into sections and reports a different BPM for each.

Can it detect tempo changes inside a song?

Yes. TempoFlow runs a sliding window over the inter-beat intervals and only registers a change once a new tempo is sustained over several windows. This avoids false positives from drummer jitter while still catching real shifts at section boundaries (verse → chorus, half-time breakdowns, etc.).

What is "beat offset" and why does it matter?

Beat offset is the time from the start of the audio to the first beat, expressed as a phase offset relative to the beat period. If beat offset is wrong, every beat line will be shifted equally, so calibrating it is the easiest way to lock the grid onto the music. TempoFlow normalises the offset into a single beat period (0 ≤ offset < 60000 / BPM ms) so it stays human-readable.

How do I correct a section's BPM by hand?

Each section row has a BPM input (integers only) and ×½ / ×2 buttons. The ratio buttons are useful when the algorithm picks up on the half- or double-time pulse — common with drum-and-bass or slow ballads. After changing the BPM you can use the metronome click button on the player to confirm the grid sounds right.

What format is the exported JSON?

The exported file contains the song name, a global tempo, a beat offset (ms), and a list of customTempoSections with each entry's start time and BPM. The structure is suitable for rhythm-game beat configuration workflows that consume per-section tempo data.

Is my audio file uploaded somewhere?

The MP3 is sent to the analysis API for processing only. It is not stored, logged, or used for any other purpose, and there is no account system. The waveform you see in the browser is rendered locally from the file you selected.

Is TempoFlow free?

Yes. The tool is free to use without sign-up. If you find it useful, share the site or link to it from your guides — that helps other rhythm-game players find it.

Which file formats are supported?

MP3 is supported today. WAV and OGG support is on the roadmap; if you need them, drop a note in the contact page.

Can I use TempoFlow for music that isn't for a game?

Absolutely. DJs, producers, choreographers, and music students use BPM tools every day. The exported JSON also works as a generic beat-grid description for video editors, click-track generation, or DAW import via custom scripts.