MuscleOS

Privacy Policy

Last updated: October 8, 2026

1. Introduction

MuscleOS ("we", "our", or "us") is committed to protecting your privacy. This Privacy Policy explains how we collect, use, disclose, and safeguard your information when you use our mobile application and related services. Your workout data is yours — we do not sell it, and we do not use it for advertising.

2. Information We Collect

MuscleOS is local-first. You can log workouts without creating an account, and the app works offline.

  • On-device workout data. Sessions, templates, notes, custom exercises, recovery derived from your sessions, and settings (units, theme, sounds, optional biodata) stay on your device by default.
  • A guest identifier. On first launch the app signs you in as an anonymous guest with Supabase. This creates a random user ID with no name or email attached. If you later sign in with Apple or Google, it is used to keep the workouts you already logged. Guest workouts are not uploaded.
  • Account information, if you link an account. Email address (or Apple Hide My Email relay), and a display name if you provide one. Sign in is available via Apple (iOS), Google, or email. Cloud backup is one MuscleOS account per email: Apple, Google, and password with the same address are the same account.
  • Synced copy, if you link an account. We store a backup of your sessions, templates, folders, exercise notes, custom exercises, previous-set snapshot, and app settings so you can restore them on another device. Recovery is not synced; it is recomputed locally from your sessions.
  • Optional biodata you enter. Body weight, age, and sex. Used for in-app features (the body diagram and strength standards). It is included in the synced copy if you link an account. We do not collect health-sensor data and we have no HealthKit or Google Fit integration.

The app also downloads the shared exercise catalog from our servers; that request contains no workout data. We do not use analytics, crash-reporting, or advertising SDKs, in the app or on this website, and we do not sell your personal information.

3. How We Use Your Information

We use this information to run the MuscleOS app: to save and restore your training log, to sync a linked account across devices, and to respond when you contact us. We do not use your workout history for advertising or sell it to third parties.

4. Third Parties

We share only what each service needs to do its job:

  • Supabase — guest and account sign-in, the synced copy of your workout data, and the exercise catalog.
  • Apple — Sign in with Apple (iOS).
  • Google — Sign in with Google.

Those companies process data under their own privacy policies. We do not receive or store your full payment card number.

5. Data Storage and Security

Local data lives in app storage on your device. When a linked account syncs, data is transmitted over HTTPS. You are responsible for the security of your device and any account credentials.

6. Your Rights

Depending on your location, you may have rights to access, correct, delete, or export your personal data.

  • Export. Profile → Account → Data → Export my data writes a JSON file you can share. It is a portability copy of your history, not a full backup, and the app has no import.
  • Clear this device. Profile → Account → Data → Clear all data removes your saved workouts, templates, and settings from this phone. You stay signed in. If you are signed in, your synced copy is kept and syncs back to the phone; delete your account to remove it.
  • Delete your account. If you have linked an account, open Profile → Account → Delete account. That removes the account and the synced copy from our systems, revokes Sign in with Apple if you used it, wipes this device, and leaves you as a guest. Short-term backups required for security or legal compliance may linger briefly. Uninstalling the app also removes local data. You can also delete the account without the app at muscleos.app/delete-account.

7. Contact Us

Questions about this policy, an export, or account deletion: support@muscleos.app. You can also delete a linked account in the app as described above.