Privacy Policy

Last updated: 22 March 2026

1. Who we are

Crystal Index (“we”, “us”, “our”) is operated by Monkey Taps Ltd. Our website is crystalindex.co.uk and our iOS app is available on the App Store.

2. Data we collect

iOS app (local-first): Your crystal collection is stored locally on your device using SwiftData. If you have an active premium subscription, your data may sync to your personal iCloud account via CloudKit — this data is controlled entirely by Apple and is not accessible to us.

Photos you take: Photos you add to your crystal collection are stored locally on your device (or in your iCloud if CloudKit sync is enabled). We do not upload your photos to our servers.

AI identification: When you use the AI crystal identification feature, the photo you submit is temporarily uploaded to our secure image store and sent to DeepInfra for processing using their vision model. The image may be retained briefly for processing purposes. Please review DeepInfra's privacy policy for their data handling practices. We do not use your images to train AI models.

Purchases: Subscriptions are managed via RevenueCat and Apple's App Store. We receive anonymised purchase data (subscription status, product ID) but do not receive your payment details.

Analytics: Our website uses PostHog to collect anonymised usage analytics (page views, feature usage). No personally identifiable information is collected.

3. How we use your data

We use the data described above to:

  • Provide and improve the Crystal Index app and website
  • Process your subscription and verify your premium entitlement
  • Respond to support requests
  • Understand how users interact with the app (anonymised analytics only)

3a. Camera and photo library

The iOS app requests access to your camera and photo library solely to enable the crystal identification and collection features. This access is used only when you explicitly choose to take or select a photo. We do not access your camera or photos in the background.

4. Data sharing

We do not sell your personal data. We share data only with the following third-party service providers as necessary to provide our services:

  • Apple iCloud / CloudKit — optional data sync for premium subscribers
  • RevenueCat — subscription management and purchase verification
  • DeepInfra — AI crystal identification via vision model (images only, not stored by us after processing)
  • Vercel — image hosting and web infrastructure
  • PostHog — anonymised website analytics

5. Data retention

Your crystal collection data is stored on your device and/or your personal iCloud account. You can delete this data at any time by deleting the app or clearing app data through iOS Settings. We do not maintain server-side copies of your collection.

6. Your rights

Depending on your location, you may have rights under applicable data protection law (including GDPR if you are in the EU/UK) to access, correct, or delete your personal data. To exercise these rights, please contact us at the email address below.

7. Children's privacy

Crystal Index is not directed at children under the age of 13. We do not knowingly collect personal data from children under 13.

8. Changes to this policy

We may update this Privacy Policy from time to time. We will post the revised policy on this page with an updated date. Continued use of Crystal Index after any changes constitutes your acceptance of the new policy.

9. Contact us

If you have any questions about this Privacy Policy, please contact us at: hello@crystalindex.co.uk