Back tap — what we collect
Live BPM can count a tap on the back of your phone as a press of Tap. Whether a knock is a real tap or your hand shifting is decided by a small model, and that model was fitted on motion recorded by one person, on one phone, in one case. It has never seen your hands.
If you allow it, your phone can send a little of that motion back, so the model learns from more than one pair of hands. This page says exactly what that means.
This is entirely optional. Back tap works the same whether you allow it or not, and nothing on this page happens unless you tap Allow.
1. The short version
- We send one second of motion around each knock the phone detects — never a continuous recording.
- There is no account, no device ID, and no identifier of any kind. Contributions cannot be traced back to you, not even by us.
- Uploads happen only on Wi-Fi.
- The data is used for one purpose: improving back-tap detection. Nothing else.
- You can turn it off at any time in Account → Help improve back tap.
2. What is actually sent
When back tap is switched on, the app watches the accelerometer and gyroscope for the sharp impulse a fingertip makes. When it finds one — whether or not it decides it was a tap — it keeps a short window around it:
- 0.6 seconds before and 0.4 seconds after the impulse, from the accelerometer and the gyroscope;
- a handful of numbers describing what the app thought at that moment: how noisy the phone was, which way gravity was pointing, whether it decided you were holding it, walking, or touching the screen, and the score its model gave the knock;
- which situation the phone was in: the back-tap tutorial, a live tempo count, or switched on but idle.
One such window is about 1.3 kilobytes. They are sent in batches of thirty, so a batch is roughly 40 KB — a fraction of one photo.
Nothing is written down until a knock is detected. There is no rolling recording of your movement, and the app does not read motion at all while back tap is switched off.
3. What is never sent
- Your name, email, or account — the upload carries no login and is not linked to your Live BPM account even when you are signed in.
- Any advertising identifier, device identifier, or installation identifier.
- Location, in any form.
- Audio. The microphone is not involved in back tap at all.
- Free text of any kind. There is no field for it.
- The exact time of a contribution. The date is rounded to the day.
The only description of your phone that travels with the data is its model (for example, “Pixel 10 Pro”), its major operating-system version, and the app version. Sensors differ between models, so a corpus that cannot tell two phones apart cannot tell whether an improvement works on both.
Like any internet request, the upload reaches our provider (Supabase) from an IP address. We do not store it alongside the data and we do not use it. It appears only in our provider’s own short-lived request logs.
4. Why we cannot delete a contribution
Because a contribution carries no identifier, there is nothing that links it to you — and that also means there is no way to find your contributions again, and no way to delete them individually. We would rather say this plainly than imply a control that does not exist.
What you can always do is stop contributing: turn the switch off in Account. Anything still waiting on your phone is deleted immediately, and nothing further is sent.
Under the GDPR, data that cannot be linked to a person is not personal data, which is why the rights that attach to personal data (access, correction, erasure) do not apply here. That is a consequence of the design, not a way around it: we chose not to be able to identify you.
5. Consent
We ask once, right after the back-tap tutorial, with Allow and Not now given equal weight. Nothing is collected before you answer, and declining is final — we do not ask again.
The legal basis is your consent (GDPR Article 6(1)(a)), and reading data from your device for a purpose that is not strictly necessary requires it (ePrivacy Directive, Article 5(3)). You can withdraw it at any time, in one tap, in the same place you gave it, and withdrawing is no harder than allowing.
This is separate from the analytics and advertising choices in Privacy settings. Allowing one says nothing about the other.
6. How long we keep it
Raw motion windows are deleted after 12 months. What outlives them is the fitted model — a short list of numbers that is not personal data and never was.
7. Who sees it
Contributions are stored on Supabase, our hosting provider, in a private location that is not readable by the app or by anyone without our own credentials. They are not sold, not shared with advertisers or data brokers, and not used for advertising, profiling, or any automated decision about you. They are read by us, to fit a better tap detector.
8. Age
Live BPM is not directed at children, and this page assumes the age limits set out in our Privacy Policy. If you are under that age, please do not turn this on.
9. Questions
Write to us — the address is in the Privacy Policy, which also covers everything else the app collects.