StackDay - Privacy Policy

Last Updated: April 2, 2026

StackDay (“we,” “us,” or “our”) operates the StackDay mobile application (the “App”). This Privacy Policy explains how we collect, use, disclose, and safeguard your information when you use our App. Please read this policy carefully. If you do not agree with the terms of this Privacy Policy, please do not access the App.

1. Information We Collect

Information You Provide Directly

Supplement and Tracking Data. You enter information about the supplements you take, log daily adherence, and track streaks and stats. All of this data is stored locally on your device using Apple’s SwiftData framework. We do not upload your supplement data to our servers or to third-party servers.

Communications. If you contact our support team, we collect the content of your messages and any information you provide.

Information Collected Automatically

Usage Data. We collect information about how you interact with the App, including screens viewed, features used, actions taken, the dates and times of your visits, and session duration.

Device Information. We collect device type, operating system version, unique device identifiers, and general device settings such as language and timezone.

Crash and Performance Data. We collect crash logs, error reports, and performance metrics to diagnose and fix issues.

Attribution Data. We collect information about how you discovered and installed the App, including which advertisement or campaign led to your install.

Information We Do NOT Collect

We do not upload your supplement logs, health data, or tracking data to our servers or to any third-party servers.
We do not collect precise geolocation data or track your real-time location.
We do not access your contacts, microphone, camera, or photos.
We do not use device fingerprinting or advertising identifiers (IDFA) for tracking purposes beyond install attribution.
We do not share personal data with third-party AI models or services.

2. How We Use Your Information

We use the information we collect to:

Provide, operate, and maintain the App and its features, including supplement tracking, adherence streaks, and stats
Process your subscriptions and manage premium features
Monitor and analyze usage trends and preferences to improve the App
Measure the effectiveness of our marketing campaigns and understand how users discover the App
Detect, prevent, and address technical issues, fraud, and abuse
Communicate with you about updates, support requests, and promotional offers related to the App (with your consent where required by law)
Comply with legal obligations

3. Local Data Storage

All supplement tracking data in StackDay is stored locally on your device using Apple’s SwiftData framework. Your supplement logs, adherence streaks, and stats never leave your device. We do not maintain any server-side database of your personal health or supplement data.

4. Third-Party Services

We use the following third-party services, each of which has its own privacy policy governing the data it processes:

Service	Purpose	Data Shared
PostHog	Product analytics	Anonymous usage data, screen views, feature interactions, session data
Sentry	Crash reporting and error monitoring	Device info, crash logs, anonymized usage context
AppsFlyer	Install attribution and marketing analytics	Device identifiers (where permitted), install source, in-app conversion events
Facebook SDK (Meta)	Advertising attribution and App Events	Install attribution data, anonymized conversion events
Apple StoreKit	In-app purchases and subscriptions	Purchase transactions, subscription status

We do not sell your personal data to any third party. We do not upload or share your supplement data with advertising networks or third-party services. We do not provide your data to third-party AI models or machine learning services.

All third-party service providers are contractually required to protect your data with safeguards equal to or greater than those described in this Privacy Policy.

5. Data Retention

We retain your personal data for as long as the App is installed or as needed to provide you services. Specifically:

Supplement tracking data is stored on-device and never stored on our servers.
Analytics data is retained for up to 12 months.
Crash and performance logs are retained for up to 90 days.
Communication records (support emails) are retained for up to 24 months.

When you delete the App, all locally stored data is removed from your device.

6. Data Security

We implement reasonable administrative, technical, and physical safeguards to protect your personal data, including:

All supplement and tracking data is stored locally on your device — it never leaves your device
All data stored locally using iOS system-level encryption
No server-side storage of your supplement logs or personal data

No method of electronic transmission or storage is 100% secure. While we strive to protect your personal data, we cannot guarantee its absolute security.

7. Your Rights and Choices

Depending on your location, you may have the following rights:

Access. Your data is stored on your device and accessible to you directly within the App at all times.
Deletion. Deleting the App removes all locally stored data.
Opt Out of Analytics. You can limit analytics collection by disabling “Allow Apps to Request to Track” in iOS Settings > Privacy & Security > Tracking.

To exercise any of these rights or with questions, please contact us at ben@thefoghill.com. We will respond within 30 days.

8. Children’s Privacy

The App is not directed to children under the age of 13. We do not knowingly collect personal data from children under 13. If we learn that we have collected personal data from a child under 13, we will take steps to delete that data promptly. If you believe that a child under 13 has provided us with personal data, please contact us at ben@thefoghill.com.

9. International Data Transfers

Your data may be processed in the United States or other countries where our service providers operate. By using the App, you consent to the transfer of your data to these jurisdictions, which may have data protection laws that differ from those in your country.

10. California Privacy Rights (CCPA/CPRA)

If you are a California resident, you have additional rights under the California Consumer Privacy Act (CCPA) and the California Privacy Rights Act (CPRA):

The right to know what personal data we collect, use, and disclose
The right to request deletion of your personal data
The right to opt out of the sale of personal data — we do not sell your personal data
The right to non-discrimination for exercising your privacy rights

To exercise these rights, contact us at ben@thefoghill.com.

If you are located in the European Economic Area (EEA) or United Kingdom, we process your data under the following legal bases:

Contract performance: To provide the App and its features as described in our Terms of Service
Legitimate interests: To improve the App, prevent fraud, and ensure security
Consent: For optional features like push notifications

Under the GDPR, you have the right to:

Access the personal data we hold about you
Rectify inaccurate personal data
Request erasure of your personal data
Restrict or object to the processing of your personal data
Data portability — receive your data in a structured, machine-readable format
Withdraw consent at any time where processing is based on consent

You have the right to lodge a complaint with your local data protection authority if you believe your rights have been violated.

To exercise these rights, contact us at ben@thefoghill.com. We will respond to verified requests within 30 days.

12. Changes to This Privacy Policy

We may update this Privacy Policy from time to time. We will notify you of material changes by posting the updated policy in the App and updating the “Last Updated” date. Your continued use of the App after any changes constitutes your acceptance of the revised policy.

13. Contact Us

If you have questions about this Privacy Policy, please contact us:

Email: ben@thefoghill.com

This Privacy Policy is effective as of April 2, 2026.