TempoTango - BPM & Key Analyzer

Detect the BPM and musical key of the track playing in your active tab. Built for DJs prepping their next set.

TempoTango is a fast, private BPM and key analyzer for tracks playing in your browser tab. Open the popup, hit Listen, and in about 40 seconds you'll get: • BPM (with octave correction so 70/140 confusion is rare) • Musical key in standard notation • Camelot wheel position for harmonic mixing • A confidence indicator on each reading Built for DJs who use SoundCloud to dig for tracks and want a quick read on whether something fits the set they're building. What makes TempoTango different • Audio is analyzed locally in your browser using essentia.js (WebAssembly). Nothing is uploaded — not the audio, not the result, not even the track URL. • No accounts, no signups, no paywalls. • No analytics, no telemetry, no third-party services. • Works on any track that plays in your active tab — including private and unreleased uploads you have access to. How it works 1. Play a track on SoundCloud. 2. Click the TempoTango toolbar icon. 3. Hit Listen. The extension captures ~40 seconds of audio from the tab and runs BPM + key detection on-device. 4. Read the result. Hit "Analyze again" if you want a second pass. Permissions • Tab capture — to read the audio of the tab you're listening to (only when you click Listen). • Offscreen — to run audio analysis off the service worker. • Active tab — to confirm the tab you're on. • Storage — to remember the most recent result while the browser is open. • soundcloud.com host access — the extension only operates on SoundCloud. Open source: TempoTango is AGPL-3.0 (and bundles essentia.js, also AGPL-3.0). Full corresponding source: https://gitlab.com/alexhewittx77/tempo-tango-extension