BIOS — Privacy Policy
Effective 14 September 2026. It replaces the version of 10 September 2026 — what changed is listed at the end.
The short version
BIOS reads Apple Health, works everything out on your iPhone, and sends nothing anywhere. We — the people who make BIOS — never see your health data. This page says exactly what happens to it, and the little we do process when you write to us.
Who is responsible
Benjamin Kramser, Salamanderplatz 10, 70806 Kornwestheim, Germany · bios@kramser.xyz.
Your health data is processed on your device, under your control, and never reaches us — we do not receive it, store it or have any way to access it. We are responsible in the GDPR sense only for the two things described under When you write to us and What Apple may share with us.
What BIOS reads
With your permission, from Apple Health: steps, heart rate, resting heart rate, heart rate variability, exercise minutes, active energy, workouts and their distance, sleep, VO₂ max, wrist temperature, blood oxygen, respiratory rate, height, body mass, and your date of birth and biological sex.
It reads these to calculate your BIOS Age and your daily Recovery, Sleep and Strain readings. Nothing is requested that no reading uses.
Where it goes
Nowhere. BIOS makes no network requests. There is no account, no sign-in, no server, no analytics, no advertising and no tracking. Your readings are not uploaded, not shared, and not sold.
Calculated readings are stored in an app database on your iPhone so the app can open without re-reading months of Health data. That database is not synced to iCloud and is excluded from iCloud and computer backups — it is a cache, and BIOS rebuilds it from Apple Health if it is ever missing. Like the rest of your iPhone, it is protected by your passcode.
BIOS does not write anything into Apple Health.
On your Apple Watch
If you install the Watch app, your iPhone sends it a small snapshot — your BIOS Age, how it has changed, and the past seven days' readings — over Apple's encrypted link between your own devices. The Watch keeps the latest snapshot so its screens and complications work without the phone. Nothing else goes to the Watch, and the Watch sends nothing anywhere. Removing the Watch app removes the snapshot.
Notifications
BIOS can notify you: a morning update with your Sleep and Recovery readings, a Strain update after a workout, a note when your BIOS Age changes. They are optional — iOS asks before the first one, and each kind can be turned off in BIOS → Settings. They are created on your iPhone, not sent through a server. Because a notification can show a reading on your lock screen, your iPhone's lock-screen settings decide who can see it there.
To keep readings and notifications current, iOS may wake BIOS briefly in the background when Apple Health records new data. That processing stays on the device like everything else.
Your control
- Revoking access. Settings → Privacy & Security → Health → BIOS turns any category off. BIOS keeps working with what is left and says which readings it can no longer make.
- Deleting everything. Deleting the app removes its database, its settings and everything BIOS calculated; deleting the Watch app removes the snapshot there. Your Apple Health data is untouched — it was never ours. There is no copy anywhere else to request the deletion of, because there is nowhere else.
- No profiling. BIOS does not build a profile of you for anyone else, and it cannot: nothing leaves the device.
When you write to us
If you email bios@kramser.xyz, we process your address and what you write in order to answer you and to keep a record of the conversation (Art. 6(1)(b) and (f) GDPR). Mail is kept while the conversation is open and for up to two years afterwards, then deleted. Please don't send health data by email — we don't need it to help you, and email is not a safe place for it.
What Apple may share with us
Apple runs the App Store. If you have opted in under Settings → Privacy & Security → Analytics & Improvements → Share with App Developers, Apple may pass us anonymised crash logs and usage statistics for BIOS. They contain no Health data and no readings; Apple decides what is in them and describes it in its own privacy policy. We use them only to fix bugs. If you use a beta of BIOS through TestFlight, Apple's TestFlight terms cover the crash reports and feedback you send.
Children
BIOS is not directed at children. Its BIOS Age calculation is blocked below 18 because the published evidence it rests on does not cover that age.
Not a medical device
BIOS is for information only. It does not diagnose anything, it is not a medical device, and it cannot see your medical history. Talk to a healthcare provider about health questions.
Your rights
Because we hold no health data about you, there is nothing for us to give you access to, correct or delete — you already hold all of it, in Apple Health and on your devices. For what we do hold (your emails), you have the rights in Art. 15–21 GDPR: write to bios@kramser.xyz. You may also complain to a supervisory authority; the one responsible for us is Der Landesbeauftragte für den Datenschutz und die Informationsfreiheit Baden-Württemberg, Heilbronner Straße 35, 70191 Stuttgart.
Changes
When this policy changes, the date at the top changes, the new text appears inside the app (Settings → Privacy) and at kramser.app/bios/privacy, and BIOS will not start doing anything new with your data without saying so here first.
14 September 2026 — added: the Apple Watch, notifications and background updates, backups, what we process when you write to us, what Apple may share with us, your rights, who is responsible. Effective 10 September 2026 was the first version.
Contact
bios@kramser.xyz — Imprint: https://kramser.xyz/en/imprint
This is the policy of the BIOS app, identical to the text inside the app. The website itself has its own privacy notice; the legal notice is the Impressum.