Privacy Policy

Last updated: July 23, 2026

Tongue is a wellness journaling app operated by 4DHD, Inc. (“we,” “us,” “our”). This policy explains what information the app handles, why, and the choices you have. We built Tongue to work without an account, name, or email, and this policy reflects that.

The short version. We don’t ask for your name, email, or password. Your journal is tied to a random identifier generated on your device — not to you personally. Your tongue photos are used only to generate your reading and to build your private history. We don’t sell your data.

1. Who we are

4DHD, Inc. is the data controller for information processed through the Tongue app. You can reach us at contact@4dhd.org.

2. Information we handle

Information you provide

Tongue photos. Images you capture in the app so they can be analyzed and saved to your history.
Notes and context tags. Optional free-text notes and tags (e.g. “Poor sleep,” “Alcohol”) you attach to a reading.

Information created automatically

A random device identifier. When you first open the app, it generates a random UUID that is stored on your device and sent with requests to identify your journal. It is not derived from your identity and is not linked to any account.
Reading results. The analysis and scores generated from each photo, plus timestamps, stored as your history.
Subscription status. Whether you hold an active Tongue Pro subscription, managed through RevenueCat (see subprocessors below). We do not receive or store your payment card details — those are handled by Apple or Google.

Stored only on your device

Your reminder schedule and notification preferences. Reminders are scheduled locally on your device; we do not run a server that tracks them.

What we do not collect

We do not collect your name, email address, phone number, precise location, contacts, or health data from other apps or devices. We do not use third-party advertising or cross-app tracking.

3. How your photos are processed

When you capture a reading, the image is uploaded to our storage on Cloudflare and sent to Google’s Gemini API to generate the tongue analysis. The result is returned to the app and saved to your history. Photos are processed to provide the service to you — not for advertising, and not to train third-party models on your identity.

4. Why we process this information

To analyze your tongue photo and produce your reading.
To store and display your private journal, history, and trends.
To operate the free-first-reading model and manage Tongue Pro subscriptions.
To let subscribers recover their journal on a new device (see Retention).
To maintain the security and reliability of the service.

5. Subprocessors

We share information only with the service providers that make the app work, and only as needed:

Provider	Purpose
Cloudflare, Inc.	Hosting, image storage (R2), and database (D1) for your journal
Google LLC	Gemini API — analysis of tongue photos
RevenueCat, Inc.	Subscription management and entitlement status
Apple / Google	App distribution and subscription payment processing

These providers process data on our behalf under their own terms and security commitments. We do not sell your personal information, and we do not share it for cross-context behavioral advertising.

6. Data retention and deletion

Your journal is retained so you can access your history over time. Because your data is keyed to an on-device identifier:

Durable, cross-device backup is provided to subscribers. If you subscribe and later restore purchases on a new device, your journal can be reunited with you.
For free users, journal data is tied to the identifier on your device and may not persist if the app is uninstalled or the device is reset.

You may request deletion of the data associated with your device at any time by emailing contact@4dhd.org. Because we don’t hold identifying details, we may ask for information that helps us locate the correct records (such as your in-app device identifier), and we’ll delete your photos and history from our storage.

7. Security

Data is transmitted over encrypted connections (HTTPS) and stored with our infrastructure providers. No method of transmission or storage is completely secure, but we work to protect your information and limit access to it.

8. International processing

We operate from the United States, and our providers may process and store data in the United States and other countries. By using Tongue, you understand that your information may be processed in these locations.

9. Children’s privacy

Tongue is not directed to children under 13, and we do not knowingly collect information from them. If you believe a child has provided us information, contact us and we will delete it.

10. Not medical advice

Tongue is a wellness and self-reflection tool. It does not provide medical advice, diagnosis, or treatment. See our Terms of Service for details.

11. Changes to this policy

We may update this policy from time to time. When we do, we’ll revise the “Last updated” date above, and material changes will be reflected in the app or on this page.

12. Contact

Questions or requests? Email contact@4dhd.org.