Privacy Policy

Last updated: 1 November 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 events from the extension (which features are used, where it fails, and your country), 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 tools at keydetector.site work the same way: the analyser keeps your files in the browser tab, and the tuner and the analyser’s microphone tab listen only while you ask them to, without recording or sending the sound.

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 Your country, which our server reads from the connection (the IP address itself is not stored) Error codes when something fails (for example "no-audio"), and for code errors only the file and line where it happened Install or update, with the previous version number Trial and purchase steps (a button was shown or pressed, a trial started, a purchase finished), including which paywall was shown and what opened it, never payment details Your thumbs up or down on the chord detection, and its reason (key, chords or tempo) How long the detection took to reach a result	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
Your country, which our server reads from the connection (the IP address itself is not stored)
Error codes when something fails (for example "no-audio"), and for code errors only the file and line where it happened
Install or update, with the previous version number
Trial and purchase steps (a button was shown or pressed, a trial started, a purchase finished), including which paywall was shown and what opened it, never payment details
Your thumbs up or down on the chord detection, and its reason (key, chords or tempo)
How long the detection took to reach a result

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.

If you uninstall

When you remove the extension, Chrome opens a page on keydetector.site that asks, if you want to answer, why you left. Its address only carries the extension version. If you pick an answer, our server keeps a counter per answer, version, language and day: no identifier, no country and no free text. If you close the page, nothing is sent, so this question does not depend on the Settings switch. These counters are deleted after 180 days.

3. Your email address

If you start the free trial or buy Pro (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, your 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.
Active tab and scripting — to add the practice controls (key, speed, loop, chords) to YouTube, or to another tab after you choose "Use Key Detector on this tab".
Context menu — for that "Use Key Detector on this tab" right-click item.
Storage — for the preferences, history and optional song library described above.
Side panel — so Key Detector can stay open next to the page while you practise.
Microphone (only for the tuner and the microphone mode) — Chrome asks you first, and the sound is processed on your device and never sent.

The optional stem separation downloads its model from keydetector.site once; nothing about you or your audio is sent. Share links keep the song data after the "#" of the link, which browsers do not send to any server.

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. Visits to this website

keydetector.site counts its own visits so we know which pages and tools are useful. It uses no cookies, stores nothing in your browser and loads no third-party script: each page sends one anonymous message to keydetector.site itself with the page address (without anything after “?” or “#”), the kind of site you came from (for example “Google”, “YouTube” or “typed in”, never the address of that page), whether you are on a phone, a tablet or a computer, whether your browser can install Chrome extensions, and the page language. Our server adds your country, as Cloudflare reports it, and keeps only a counter per day for each combination. No identifier, IP address, browser name or version, or anything you analyze is stored, so a visit can’t be linked to you or to another visit.

Some actions are counted the same way, by name only: analyzing a file or the microphone, exporting, using a tool (tap BPM, metronome, transposer, Camelot wheel, tuner) and pressing a button that leads to the Chrome Web Store. Links to the store carry the name of our page and button (utm tags), so the store’s statistics show which page brought an installation. If your browser sends Global Privacy Control or Do Not Track, nothing is counted. These counters are deleted after 180 days. The page that opens when you remove the extension (section 2) does not send this.

9. 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.

10. 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.

11. Contact

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