Privacy Policy

Last updated: 2026-06-05

This Privacy Policy explains what information Kronos collects, how we use it, and the choices you have. It applies to the Kronos mobile application and related services, which are operated by Muller Labs, LLC (“we,” “us”), the data controller for the personal information described here. Our contact details appear at the end of this Policy.

1. Information You Provide

When you create an account and use the Service, we collect:

• Account details: email address, display name, locale, and region.
• Fitness preferences: gender, date of birth, self-reported fitness level, primary training goal, and any free-text notes you enter in the “injuries” or “guidelines” fields.
• Equipment and locations: names of training locations and lists of equipment you tell us are available.
• Workout activity: the workouts generated for you, the sessions you start, time spent active, exercises modified or skipped, perceived difficulty ratings, and any notes you add.
• Exercise feedback: love/like/neutral/dislike/hate ratings you assign to individual exercises.
• Feedback submissions: messages, optional screenshots, and the in-app context (such as which screen you were on) when you tap the feedback button.

2. Information Collected Automatically

When you use the app we automatically collect:

• AI usage data: the AI model used to generate each workout, token counts, and estimated cost. We use this to monitor system health and enforce free-tier limits.
• Device context attached to feedback submissions: app version, platform (iOS / Android / web), and current locale.
• Subscription state: whether your account currently has an active Kronos Pro entitlement, the store of purchase, and the renewal/expiry date. Payment card information is handled directly by Apple or Google and never reaches our servers.
• Product analytics events (only if analytics is enabled in your build): interaction events linked to your account ID. These are pseudonymous (they identify your account, not your name) and are used to understand which features are working and which need improvement.
• Crash and diagnostic data: when the app crashes or hits an error, our crash-reporting provider receives diagnostic events including your device model, OS version, app version, IP address, and (for a sample of sessions) a masked session replay, a screen recording in which text and images are blanked out before leaving your device. We use this to find and fix bugs.

3. What We Do Not Collect

Kronos does not request or collect any of the following:

• Apple HealthKit or Google Fit data.
• Precise or coarse location (the app does not request location permission).
• Motion or accelerometer data.
• Camera images, except screenshots you explicitly attach to feedback.
• Microphone audio.
• Contacts, calendar, or photos beyond what you explicitly share.

4. How We Use Information

We use the information we collect to:

• Provide the Service, including generating personalised workouts. The free-text contents of your preferences (including the “injuries” field) are included in prompts sent to our AI provider so that the model can take them into account.
• Authenticate you and maintain your account.
• Operate billing and entitlement features through our payment partners.
• Improve the Service, debug issues, and develop new features.
• Communicate with you about the Service, including responding to feedback and (if you opt in) sending marketing messages.
• Comply with legal obligations and protect against fraud, abuse, and harm to users or the Service.

Where laws such as the GDPR apply, our legal bases for this processing are: performance of our contract with you (providing the Service, your account, and billing), our legitimate interests (improving, securing, and debugging the Service), your consent (marketing messages and the health-related details described in the next section), and compliance with legal obligations.

5. Health-Related Information

The optional “injuries” and “guidelines” fields may contain information about your health, such as an injury, surgery, pregnancy, or medical condition. We treat that text as sensitive information: we use it only to generate your workouts, we send it to our AI provider only for that purpose, and we never use it for advertising, never sell it, and never share it except as described in this Policy.

By entering information into these fields, you expressly consent to this processing. If you prefer not to share health information, leave the fields blank; the Service works without them, and you can edit or clear them at any time in your preferences.

6. Third-Party Service Providers

We share information with the following processors who help us operate the Service:

• Convex (database and backend hosting): stores essentially all of your account data, preferences, workouts, and sessions.
• Google (Gemini API): receives the prompt content used to generate each workout, including your preferences, equipment, goals, and the free-text “injuries” and “guidelines” fields. We use the paid tier of the Gemini API, under which Google does not use this content to train its models.
• RevenueCat (subscription management): receives a pseudonymous identifier and your purchase history.
• PostHog (product analytics): receives the pseudonymous interaction events described above, when analytics is enabled.
• Sentry (crash reporting and diagnostics): receives the crash and diagnostic data described above, processed on Sentry’s European Union servers.
• Resend (transactional email): receives your email address and display name to deliver account emails such as verification codes, password resets, and welcome messages.
• Apple and Google: handle authentication and in-app purchases according to their own privacy policies.

We do not sell your personal information, and we do not share it for cross-context behavioral advertising (as those terms are defined by the CCPA).

7. International Transfers

We are based in the United States, and the providers listed above process your information mainly on servers in the United States (crash and diagnostic data is processed on Sentry’s European Union servers). If you use the Service from outside the U.S. (including Latin America, the United Kingdom, or the European Economic Area), your information will be transferred to and processed in the United States, which may have different data-protection laws than your country. Where required, we rely on safeguards such as our processors’ data-processing agreements and standard contractual clauses.

8. Data Retention

We retain your information for as long as your account is active and for a reasonable period afterward to comply with legal obligations, resolve disputes, and enforce our agreements. You may request deletion of your account at any time by emailing us at the address below.

9. Your Choices and Rights

Depending on where you live, you may have rights under laws such as the GDPR, the UK GDPR, Brazil’s LGPD, or the CCPA to access, correct, port, or delete your personal information, to object to or restrict certain processing, and to withdraw consent you have given. You also have the right to lodge a complaint with your local data-protection authority.

You may opt out of marketing communications at any time from within the app or by following the unsubscribe link in any marketing email. To exercise any of these rights, please contact us at the address below. We will not discriminate against you for exercising them.

10. Children

The Service is intended for adults aged 18 and over. We do not knowingly collect personal information from anyone under 18. If you believe a minor has provided us with personal information, please contact us so we can delete it.

11. Security

We use commercially reasonable administrative, technical, and physical safeguards to protect the information we hold. No method of transmission or storage is fully secure, however, and we cannot guarantee absolute security.

12. Changes

We may update this Policy from time to time. Material changes will be signalled by an updated version date above and a new in-app consent prompt the next time you open the app.

13. Contact

Privacy questions or rights requests can be sent to legal@kronosstudio.app, or by mail to Muller Labs, LLC, c/o Legalinc Corporate Services Inc., 131 Continental Dr, Suite 305, Newark, DE 19713, USA.