Zero Entropy Lab
Privacy Policy
Cranial Gym · Last updated: April 2026
1. Overview
Cranial Gym ("the app") is operated by Zero Entropy Lab. This policy explains what data we collect, how we use it, and your rights as a user.
2. Data We Collect
- Account data: When you create an account, we collect your email address and display name. This is stored securely in our database.
- Session data: We store your training session results including scores, XP, streaks, difficulty level, and session length to power your progress tracking and leaderboard.
- Voice recordings: When you use Sentence Recall, your voice is recorded locally on your device and sent to OpenAI's Whisper API for transcription only. Recordings are not permanently stored by Cranial Gym or OpenAI after transcription is complete.
- Device data: We collect basic usage data to maintain app functionality. We do not collect device identifiers for advertising purposes.
3. How We Use Your Data
- To provide and improve the app experience
- To display your progress, streaks, and leaderboard ranking
- To send daily training reminders (only if you enable notifications)
- To process subscription payments via RevenueCat
4. Third Party Services
Cranial Gym uses the following third party services:
- OpenAI — voice transcription (Whisper) and text-to-speech. openai.com/privacy
- RevenueCat — subscription and payment management. RevenueCat never shares your payment details with us. revenuecat.com/privacy
- InstantDB — secure database for account and session data
- Bunny CDN — delivery of sentence content
5. Data Retention
Your account and session data is retained for as long as your account is active. You can request deletion of your data by contacting us.
6. Children's Privacy
Cranial Gym is not directed at children under 13. We do not knowingly collect data from children under 13.
7. Your Rights
You may request access to, correction of, or deletion of your personal data at any time by contacting us at the email below.
8. Changes to This Policy
We may update this policy from time to time. We will notify you of significant changes via the app or email.