Privacy Policy

Last updated: October 21, 2026

1. Who we are

Fit4i ("the App") is an AI-powered personal fitness coach. This policy explains what data we collect, why, and what your rights are.

2. Data we collect

• Account data: email address, name, password (stored as a salted hash — we never see or store your plain password).
• Profile data: age, sex, height, weight, fitness goal, experience level, training equipment, injury areas, occupation activity level.
• Training data: your programs, logged workouts, sets, reps and weights.
• Nutrition data: food you log, water, body weight and supplements. If you use meal recognition, the photo or text you submit is analyzed once to estimate the meal and is not saved to your account or nutrition log.
• Health data (with your explicit consent): heart rate variability (HRV), resting heart rate, sleep stages and duration, steps, distance, active energy, blood oxygen and VO2max — from Apple Health (iOS), Health Connect (Android) or a connected wearable (e.g. Polar). We request read-only access and only the data types listed in the permission dialog.
• Apple Ads attribution (iOS): when you first sign in, the App asks Apple's AdServices framework for a one-time attribution token and sends it to our server, which asks Apple whether the install came from an Apple Ads campaign. We store Apple's answer — whether the install was attributed and, if so, the campaign, ad group, keyword and ad identifiers, country and the date of the ad tap — linked to your account. The token itself is not stored. This does not use the advertising identifier (IDFA), does not track you across other apps and websites, and needs no tracking permission.
• Usage and diagnostics data: events about how you use the App and crash and error reports (see PostHog and Sentry in section 4).

3. How we use it

• To build and adapt your training program and nutrition targets.
• To assess daily recovery (HRV, sleep) and adjust your plan.
• To estimate meals from a photo, a nutrition label or a text description, and to write the text of your daily plan (see section 4).
• Apple Ads attribution data is used only to measure which of our ads bring people who actually use the App, so we can spend our advertising budget on what helps. It is not shared with other third parties (apart from RevenueCat, see section 4) and not used to target ads to you.

We do not sell your data. We do not use your health data for advertising.

4. Processors

Our servers are hosted on Railway (US/EU infrastructure).

OpenAI. Fit4i has no AI chat. Our server sends data to OpenAI's API only in the three cases below, and only the data listed there:

• Meal recognition (Pro) — only when you use it. The meal photo or nutrition-label photo you take or choose, or the meal description you type, and, for a meal photo or description, your app language. OpenAI returns estimated foods, portions and calories/macros; you review and edit them before anything is logged.
• Food search translation. If a food search finds too few results, is not in our built-in dictionary and contains letters outside the basic English alphabet (for example Cyrillic, or accented letters such as ä or é) or your app language is German, the search text alone is sent to be translated into English, so we can also search the international food database.
• Daily plan text. When there is recent recovery data — from Apple Health, Health Connect or a connected wearable (from today or yesterday), or today's check-in — our server asks OpenAI in the background to write the text of your daily plan and tip. It sends your app language, that recovery data and the readiness status calculated by our own algorithm, and may add your profile (age, sex, height, weight, goal, experience level, equipment, injury areas, training days per week, dietary preferences, your HRV baseline and which wearable you connected) and a summary of your recent recovery data (HRV, sleep, recovery score, steps) and workouts (dates, exercises, muscle groups, duration). Your readiness status is always calculated by our own algorithm, not by AI. Without recent recovery data, nothing is sent.

We never send OpenAI your name, email address, password, account ID, payment or subscription details, or Apple Ads attribution data.

Open Food Facts. When you search for a food, the search text (or its English translation) and your app language, without any information about you, may be sent to the public Open Food Facts database, for example when our own food catalog has too few matches.

PostHog (EU) — usage analytics. The App sends usage events to PostHog's EU cloud (eu.i.posthog.com): actions in the App — for example opening it, onboarding steps, starting or completing a workout, adding a food entry — with technical details such as counts, durations, the app version, device model and operating system, and an approximate location that PostHog derives from your IP address. After you sign in, events are linked to your account ID. We never send PostHog your name, email address, password, body measurements, health data or the weights you log. We use it only to understand and improve the App.

RevenueCat — subscriptions. Purchases are made through the App Store; RevenueCat verifies them and tells our server whether your Pro subscription is active. It receives your account ID, your purchase and subscription details and, on iOS, an Apple Ads attribution token so it can tell which of our ads led to a subscription. It does not receive your email address, name or health data.

Sentry (EU) — crash and error reports. When the App or our server hits an error, a report is sent to Sentry, hosted in the EU (Germany): what went wrong and where in the code, the app version, device model and operating system, and a sample of performance measurements. Reports are not linked to your account: we do not attach your name, email address or account ID to them, and Sentry is set not to collect your IP address or the contents of your requests, including health data. In rare cases the text of an error message can itself contain a detail it is about, such as an email address.

Resend — email. If you ask to reset your password, our server sends your email address and the reset link to Resend, which delivers the email. We send no other email through it.

5. Health data specifics

On iOS, health data is read from Apple Health only after you grant permission in the HealthKit dialog. You can revoke access anytime in iOS Settings → Privacy → Health.

On Android, health data is read from Health Connect only after you grant permission in the Health Connect dialog. Fit4i requests read-only access to: heart rate variability, resting heart rate, sleep, steps, distance, active and total calories, blood oxygen, floors climbed and VO2max. Fit4i never writes to Health Connect. You can review or revoke access anytime in Android Settings → Health Connect (or Security & privacy → Health Connect), and you can also disconnect the source inside the App (Settings → Health data & privacy).

On both platforms, health data is used solely to assess your recovery and adapt your training and nutrition — never for advertising or marketing, never sold, and never shared with third parties. The only processing outside our servers is the daily plan text described in section 4: when there is recent recovery data, it is sent to our processor OpenAI to write the text of your plan. Health Connect data is handled in accordance with Google Play's Health Connect data policy, including the limited-use requirements.

6. Retention and deletion

Your data is retained while your account is active. You can delete your account (and all associated data, immediately and irreversibly) in the App: Settings → Delete account, or by emailing us. Deletion removes your profile, programs, workouts, nutrition log and biometrics, as well as Apple Ads attribution data.

7. Your rights

You can access, correct or delete your data at any time from the App. For anything else, contact us at support@fit4i.com.

8. Age

Fit4i is intended for people aged 16 and older. We do not knowingly collect data from anyone younger. If you believe a person under 16 has created an account, contact us and we will delete it.