Your audio never leaves your computer.

Last updated: 2026-05-11

TempoTango is a Chrome extension that detects the BPM and musical key of audio playing in your active SoundCloud tab. This page explains what data the extension touches and what it does with it.

TL;DR. TempoTango processes audio entirely on your device. Nothing — not audio, not analysis results, not browsing activity, not personal information — is transmitted off your device by this extension. There are no analytics, no telemetry, and no third-party services contacted at runtime.

Data the extension can access

Tab audio. When you click "Listen" in the TempoTango popup, the extension uses Chrome's tabCapture API to read approximately 40 seconds of audio from your active SoundCloud tab. The captured audio is held in browser RAM only for the duration of analysis. It is never written to disk, never persisted across browser sessions, and never transmitted off your device. The buffer is discarded as soon as analysis completes.
Active tab URL. The extension reads the URL of your active tab to verify you are on soundcloud.com before attempting capture. The URL is not logged or transmitted.

Data the extension does not access

The extension does not read any other tabs, browsing history, bookmarks, cookies, saved passwords, autofill data, or other extensions' data.
The extension does not request <all_urls> host permissions; access is restricted to soundcloud.com and its subdomains (*.soundcloud.com), as declared in the manifest.
The extension does not ask for microphone access, screen capture, geolocation, or any other sensitive permissions.

How analysis works

The captured audio is processed by essentia.js, a WebAssembly audio analysis library bundled inside the extension. All processing runs in the offscreen document (a hidden tab inside the extension itself). No network requests are made during or after analysis.

Storage

The extension uses chrome.storage.session to remember the most recent analysis status and result while the browser is open, so closing and reopening the popup does not lose your in-progress analysis. Session storage is automatically cleared by Chrome when the browser is closed. No data is written to persistent (local or sync) storage and nothing is sent off the device.

Third parties

The extension bundles essentia.js (AGPL-3.0). It is included as static files at install time and does not phone home.

The extension does not use any analytics, crash reporting, advertising, or third-party telemetry services.

Your control

You can revoke all access immediately at any time by uninstalling the extension from chrome://extensions. Uninstalling stops tabCapture and clears the session-storage state described above. Because no data is written to persistent storage, no residual data remains on your device after uninstall, and nothing was ever sent off-device for us to delete.

Your rights (GDPR / CCPA / similar)

Because TempoTango does not collect, store, sell, share, or transmit any personal data, there is no personal information for us to access, export, correct, or delete on request. If you believe this is incorrect, please contact us using the details below.

Children

TempoTango is not directed at children under 13. We do not knowingly collect any data from any user, of any age.

Permissions justification

Required by the manifest for legitimate functionality:

tabCapture — read tab audio to analyze it. Used only when the user clicks Listen.
offscreen — run the analysis in a hidden DOM context (Manifest V3 service workers cannot use Web Audio).
activeTab — confirm the active tab is on SoundCloud.
storage — used to persist in-progress analysis state and the most recent result to chrome.storage.session, so closing and reopening the popup does not lose the active analysis. Nothing is written to persistent (local or sync) storage.
Host permissions https://soundcloud.com/* and https://*.soundcloud.com/* — restrict the extension to SoundCloud and its subdomains.

Changes

If this policy changes, the updated version will be posted on this page with a new "Last updated" date. Material changes (e.g., introducing any kind of network transmission) will be called out in the extension's release notes.

Contact

TempoTango is a personal project. For privacy questions, bug reports, or feedback, email hello@tempotango.co.