Privacy Policy

Last updated: May 15, 2026

Day Zero ("we," "us," or "our") operates the Day Zero mobile application. This page informs you of our policies regarding the collection, use, and disclosure of personal information when you use our app.

      The short version: We collect only what we need to run the app. Your health data stays on your device. We never sell your data. Ever.
    

1. Information We Collect

Account Information: When you create an account, we collect your email address and authentication credentials. If you sign in with Apple or Google, we receive the identifier provided by those services.

Onboarding Data: During onboarding, you provide information about your drinking patterns, goals, and motivations. This data is used solely to personalize your experience and calculate your progress metrics.

Usage Data: We collect information about how you use the app, including craving events, daily check-ins, and drink logs. This data is used to provide you with insights and track your progress.

2. Health Data

Apple Health / Google Health Connect: With your explicit permission, we read sleep duration, resting heart rate, and heart rate variability data from Apple Health (iOS) or Health Connect (Android).

      Important: Health data retrieved from Apple Health or Google Health Connect is used solely to compute your "sleep gained" metric and is displayed only to you. We do not store raw health data on our servers, transmit it to third parties, or use it for advertising purposes.
    

3. How We Use Your Information

We use the information we collect to:

Provide and maintain the Day Zero app
Calculate your personalized progress metrics (streak, money saved, sleep gained, calories avoided)
Send push notifications for daily check-ins and milestone celebrations (with your permission)
Improve the app experience through anonymized, aggregated analytics
Process subscription payments through Apple App Store or Google Play Store

4. Data Sharing

We do not sell, rent, or trade your personal information. We share data only with:

Supabase: Our database provider, which stores your account and app data with encryption at rest
RevenueCat: Our subscription management provider, which processes payment status (not payment details)
PostHog: Our analytics provider, which receives anonymized usage events
Apple / Google: Payment processing through their respective app stores

5. Data Security

We implement industry-standard security measures including encryption in transit (TLS), encryption at rest, and row-level security policies ensuring users can only access their own data. However, no method of transmission over the Internet is 100% secure.

6. Data Retention and Deletion

We retain your data for as long as your account is active. You can delete your account at any time from the Settings screen in the app. When you delete your account:

All personal data is permanently removed from our servers
All craving events, drink logs, check-ins, and health metrics are deleted
This action is irreversible

7. Your Rights

You have the right to:

Access the personal data we hold about you
Request correction of inaccurate data
Request deletion of your data (via in-app account deletion)
Withdraw consent for health data access at any time through your device settings
Opt out of push notifications through your device settings

8. Children's Privacy

Day Zero is not intended for use by anyone under the age of 18. We do not knowingly collect personal information from children.

9. Changes to This Policy

We may update this Privacy Policy from time to time. We will notify you of any changes by posting the new policy on this page and updating the "Last updated" date.

10. Contact Us

If you have questions about this Privacy Policy, contact us at hello@dayzer0.app.

11. Disclaimer

Day Zero is a lifestyle and wellness application. It is not medical advice. If you are physically dependent on alcohol, please consult a healthcare professional before making changes to your drinking habits, as withdrawal can be medically dangerous.