Privacy Policy

Last updated: March 24, 2026

StrengthCharts ("we", "our", or "the app") is a personal strength-training tracker available on iOS, Android, and the web. We take your privacy seriously. This policy explains what data we collect, why we collect it, and how we protect it.

1. Information We Collect

Account Information

When you create an account, we collect:

Username — used to identify your account and let friends find you
6-digit PIN — securely hashed (bcrypt) and never stored in plain text
Display name — shown to friends on leaderboards and profiles
Email address — used only for PIN reset codes

Fitness & Body Data

Lift logs — exercise name, weight, reps, RPE, notes, and date
Bodyweight logs — weight and date
Body measurements — waist, body fat %, neck, chest, biceps, and other measurements you choose to log

Profile Data

Profile photo — stored as compressed image data in your account
Preferences — weight unit (lbs/kg), theme color, sex (for strength standards), privacy settings
Showcase badges — achievement badges you select to display

Social Data

Friend connections — who you are friends with and pending requests
Group memberships — groups you create or join

Apple Health Data iOS only

If you enable Apple Health integration, we read and write:

Bodyweight and body fat percentage
Workout and sleep session data (read only)

Apple Health data is accessed on-device only and is never transmitted to our servers. This integration is entirely optional and can be disabled at any time in Settings.

Purchase Information

In-app purchases (Pro subscription) are processed by Apple (App Store) or Google (Play Store) through RevenueCat. We receive confirmation of your subscription status but never see or store your payment details.

Advertising

We use Google AdMob to display optional rewarded ads that temporarily unlock Pro features. AdMob may collect device identifiers and usage data as described in Google's Privacy Policy. You are never required to watch ads — they are entirely opt-in.

2. How We Use Your Data

Data	Purpose
Account info	Authentication, account recovery, displaying your name to friends
Lift & body data	Tracking your personal records, calculating strength tiers, generating charts and statistics
Profile photo	Displayed on your profile and to friends
Friend/group data	Social features: leaderboards, challenges, group competitions
Email address	Sending PIN reset codes only — we do not send marketing emails
Privacy settings	Controlling what friends can see on your profile
Purchase status	Unlocking Pro features you have paid for

3. How We Store & Protect Your Data

All data is stored in a Turso (SQLite) cloud database hosted in the US (AWS us-east-2)
PINs are hashed using bcrypt with a unique salt per user
All API communication uses HTTPS/TLS encryption in transit
Authentication uses JWT tokens that expire after 14 days
Security headers prevent clickjacking, XSS, and content-type sniffing attacks
Rate limiting protects against brute-force login attempts
Weights are stored internally in kilograms and converted to your preferred unit on display only

4. Data Sharing

We do not sell, rent, or share your personal data with third parties, except:

Friends you add — can see your display name, profile photo, and data you have not marked private via your privacy settings
RevenueCat — receives anonymized purchase data to manage subscriptions
Google AdMob — may collect device-level identifiers when you choose to watch a rewarded ad
Resend — receives your email address only when you request a PIN reset code
Law enforcement — if required by law or valid legal process

5. Your Privacy Controls

You have full control over your data visibility:

Privacy toggles in Settings let you hide PRs, lifts, bodyweight, and achievements from friends
Apple Health sync can be enabled or disabled at any time
Ad tracking can be limited via your device's system settings (iOS: Settings > Privacy > Tracking; Android: Settings > Privacy > Ads)

6. Data Retention & Deletion

Your data is retained as long as your account exists. You can delete your account at any time from the Settings page. Account deletion permanently removes:

Your user account and profile
All lift logs and personal records
All bodyweight and body measurement logs
All friend connections and group memberships
All routine data

Deletion is immediate and irreversible. Locally cached data (workout history, group photos, preferences) is stored on your device and can be cleared by uninstalling the app.

7. Children's Privacy

StrengthCharts is not directed at children under 13. We do not knowingly collect personal information from children under 13. If you believe a child under 13 has created an account, please contact us and we will delete it promptly.

8. International Users

Our servers are located in the United States. By using StrengthCharts, you consent to the transfer and processing of your data in the US. We handle data in accordance with applicable privacy laws.

9. Changes to This Policy

We may update this privacy policy from time to time. Changes will be reflected by updating the "Last updated" date at the top of this page. Continued use of the app after changes constitutes acceptance of the updated policy.

10. Contact Us

If you have questions about this privacy policy or your data, contact us at:

StrengthCharts@gmail.com