Privacy Policy

Last updated: 9 October 2026 · Applies to the Key Detector Chrome extension and to keydetector.site

Key Detector analyses audio on your device. Your audio and your files are never uploaded to us, and there is no account to create.

The short version. We receive three things: anonymous usage counts from the extension, including which YouTube videos are used most, counted without knowing who used them (you can switch all of it off), your email address if you buy Pro or start the free trial, and your email address if you subscribe to the newsletter. Nothing else.

1. Audio and files

Detection runs entirely inside your browser. Tab audio, microphone input and the files you open are processed locally and are never transmitted, stored or shared. The web analyser at keydetector.site works the same way: your files stay in the browser tab.

2. Anonymous usage data

From version 2.0 the extension sends anonymous counts to our own server (a Cloudflare Worker) so we can see which features are used and where the product fails. Each batch carries a random identifier generated on your device, which is not linked to your email or to any account.

We do send	We never send
Feature used (a detection finished, chords opened, chart printed, a tool like transposition or the player) The kind of site the audio came from (YouTube, Spotify, another website, a file), never its address Analysis length in seconds and confidence level (low / medium / high) Whether a tempo was found, and how many chords were recognised Extension version, interface language, operating system Whether the licence is Pro or free	Audio, of any kind Page addresses, video titles or file names (YouTube videos: see below) The detected key, mode or tempo Your email address Your IP address, which our server does not store

We do send

We never send

Feature used (a detection finished, chords opened, chart printed, a tool like transposition or the player)
The kind of site the audio came from (YouTube, Spotify, another website, a file), never its address
Analysis length in seconds and confidence level (low / medium / high)
Whether a tempo was found, and how many chords were recognised
Extension version, interface language, operating system
Whether the licence is Pro or free

Audio, of any kind
Page addresses, video titles or file names (YouTube videos: see below)
The detected key, mode or tempo
Your email address
Your IP address, which our server does not store

You can turn this off at any time in Settings → Help improve Key Detector. When it is off, nothing is sent and anything pending is discarded. These counts are deleted automatically after 180 days.

Which songs are used most

When you detect, show chords or use Studio on a YouTube video, the extension sends the video's public identifier (the 11 characters after watch?v=) and which of those three things you did. It travels on its own: without the random identifier above, without your country and without the time of day. Our server only keeps a counter per video and day, so it can tell which songs are popular but not who listened to them or what else they did. Each video is counted at most once a day per device. The title is looked up from YouTube by us when we read the totals; it never comes from your browser. Nothing like this is sent for Spotify or any other site: only the kind of site. The same switch in Settings turns it off, and these counters are deleted after 180 days.

3. Your email address

If you start the free trial or buy Pro (monthly, yearly or lifetime), your email address is processed by ExtensionPay and Stripe to create and restore your licence, and by Stripe to take the payment. We never see your card details. If you subscribe to the optional email guide, your address is processed by Brevo with double opt-in, and every message has an unsubscribe link.

4. Stored on your device

Your analysis history, preferences, beta ratings and licence status are kept in Chrome's local storage on your computer. If you use the Pro song library, it also keeps your song titles, YouTube video links or file names, chosen keys, tempo, practice settings, notes and derived chord charts there. The original audio is never saved in the library or sent to us. Uninstalling the extension removes these local records.

5. Permissions the extension asks for

Tab capture — to analyse the audio of the tab you choose, while you ask for it.
Access to the current tab and scripting on YouTube — for Studio (transposition and speed) and for showing chords over the video.
Storage — for the preferences, history and optional song library described above.
Side panel — for the Pro panel that stays open while you browse.

The extension does not read the content of the pages you visit and does not track your browsing. It only looks at the address of the tab you use it on, to tell the kind of site and, on YouTube, the video, as described in section 2.

6. Children

Key Detector is a tool for musicians and is not directed at children under 13. We do not knowingly collect data from them.

7. Your choices

Switch the anonymous counts off in Settings.
Ask us to delete any data associated with your purchase or newsletter subscription.
Uninstall the extension, which removes everything stored on your device.

8. Videos on this website

Our videos are hosted on YouTube. On keydetector.site they load from youtube-nocookie.com only when you press play; until then the page shows an image from keydetector.site. Once a video plays, YouTube's privacy policy applies.

9. Changes

If this policy changes in a way that affects what we collect, the date at the top changes and the change is described in the extension's release notes.

10. Contact

Questions about this policy or a deletion request: hello@keydetector.site.