Privacy Policy

Last updated: June 10, 2026

Train531 (“the App”) is developed by Aaron Hampton. Train531 is available as an iOS app and as a web app at app.train531.com. This privacy policy explains how the App collects, uses, and protects your information.

Information We Collect

Account Information

Train531 uses an account to sync your training data across devices. You can sign in with Google, with Apple, or with an email address and password. We collect and store:

Your email address (from the sign-in provider you choose)
Your display name, if your sign-in provider shares it

Authentication is handled by Google Firebase Authentication.

Training Data

The App stores your workout data on your device and syncs it to your account, including:

Exercise names, sets, reps, and weights
Personal records and training maxes
Workout session dates and durations
Profile information (name, experience level, goals, available equipment)

Synced training data is stored in Google Firebase (Firestore) in a private, per-account space. Access is restricted by security rules so only you can read or write your data.

AI Coaching

When the App generates workout prescriptions or analyzes your progress, a summary of your recent training history is sent to our API server. This summary includes:

Recent workout sessions (exercises, sets, reps, weights)
Your training maxes and experience level
Available equipment

This data is forwarded to Anthropic’s Claude API to generate personalized coaching responses. AI requests are processed in real time; we do not use your training data to train AI models.

Device Information

On iOS, the App uses Apple’s App Attest to verify that AI requests come from a genuine copy of the App. A device key identifier is registered with our server for this purpose. We also record basic usage metadata for AI requests (timestamps and token counts) to operate rate limits and manage costs.

Information We Do NOT Collect

Location data
Health data (HealthKit is not used)
Contacts, photos, or other device data
Advertising identifiers
We do not sell your data to anyone

Third-Party Services

Google Firebase

Account authentication and training-data sync are provided by Google Firebase (Authentication and Firestore). Google’s privacy policy applies to these services. Visit policies.google.com/privacy for details.

Anthropic (Claude API)

Training summaries are processed by Anthropic’s Claude AI to generate workout prescriptions and progress analysis. Anthropic’s privacy policy applies to data processed by their systems. Visit anthropic.com/privacy for details.

Apple (App Store)

On iOS, subscription purchases are processed by Apple through the App Store. Apple’s privacy policy applies to these services.

Stripe

On the web, subscription payments are processed by Stripe. We do not see or store your card details. Stripe’s privacy policy applies to payment processing. Visit stripe.com/privacy for details.

Data Retention

On device: Your training data remains on your device until you delete the App or clear its data.
In your account: Synced training data remains in your account until you delete it.
AI requests: Training summaries sent for AI coaching are processed in real time and are not retained as part of your training history on our AI gateway.

To request deletion of your account and synced data, contact us at [email protected].

Data Security

All communication between the App and our servers uses HTTPS encryption. Synced data is protected by per-user security rules. On iOS, device credentials are stored securely in the iOS Keychain, and training data on your device is protected by iOS’s built-in data protection.

Children’s Privacy

The App is not directed at children under 13. We do not knowingly collect information from children.

Changes to This Policy

We may update this privacy policy from time to time. Changes will be posted on this page with an updated date.

Contact

If you have questions about this privacy policy, contact us at [email protected].