Privacy Policy

Last updated: 7 October 2026

CapDex saves the words you capture so they follow you between devices. That means we do store your data, and this page sets out exactly what we hold, where it goes, and how to get rid of it.

In short: we keep your account, your pictures and your flashcards so the App can work. We do not run ads, we do not sell your data, and we do not track your behaviour across other apps or websites.

1. Information We Collect

Account information

Signing in is required, through Apple or Google. From that sign-in we receive a user id and — depending on what you choose to share — an email address and display name. If you use Sign in with Apple’s private relay, we only ever see the relay address.

Pictures

When you capture an object, the App keeps the resulting image so the flashcard has a picture. Images are stored in Firebase Storage under a folder tied to your account, readable only by that account.

Learning data

Stored in Cloud Firestore, under your account:

words — the term in the language you are learning and in your own, pronunciation, example sentences, and the spaced-repetition schedule (interval, ease, next review date);
collections you group words into;
a review log of recent study sessions, and the days you checked in, so streaks and progress can be shown;
preferences — language pair, appearance, capture style, daily review goal, onboarding state;
a count of captures used, so the free allowance can be applied.

Purchases

If you subscribe, we receive subscription status from RevenueCat and Apple — whether an entitlement is active and when it expires. Payment itself goes through Apple. We never see your card details.

2. How We Use It

to name the object you photographed and build the flashcard;
to store your words and keep them in sync across your devices;
to schedule reviews and show your streak and progress;
to apply the free capture allowance and unlock paid features;
to keep the service running securely and to prevent abuse;
to answer you when you contact support.

We do not use your data for advertising, and we do not build profiles for marketing.

3. Third-Party Services

Google Firebase

Authentication, Cloud Firestore, Cloud Storage and Cloud Functions host the App’s backend. Your account data, cards and images live there, protected by security rules that limit access to your own account.

Google Gemini (object recognition)

To name an object, the captured picture is sent over an encrypted connection to Google’s Gemini API. The request goes through our own Cloud Function rather than straight from your phone, so our API key is never shipped inside the App. The image is used to produce that one answer; it is not used to train the model. Google may retain requests briefly for abuse monitoring, under its own terms.

RevenueCat

Manages subscription state. It receives an identifier and your purchase status — not your pictures or your words.

Apple and Google Sign-In

Used to authenticate you. Their own privacy policies govern what they collect during sign-in.

4. What We Do Not Collect

your location;
your contacts, calendar, or other apps’ data;
advertising identifiers, or any cross-app or cross-site tracking;
payment card details;
your camera roll — only the photos you deliberately capture or choose in the App.

The App carries no advertising SDKs and no third-party behavioural analytics.

5. Retention and Deletion

Your data is kept while your account exists, because it is the content of the App.

Deleting a word removes it and its picture.
Deleting your account, from the profile screen in the App, signs you out immediately and is final: the account is closed, and signing in to it again is refused.
Closing the account ends all access to what is in it. Erasing the stored words, pictures and review history is a separate step and is not automatic — ask us at the address below and we will carry it out.
If you cannot reach the App, write to support@capdex.app and we will close the account for you the same way, and erase its contents if you ask.

Backups and logs may hold residual copies for a short period before they age out.

6. Security

Data is encrypted in transit. Access is restricted per account by Firebase security rules, so one learner’s pictures and cards are not readable by another. Our AI provider’s key is held in Google Secret Manager and never ships inside the App. No system is perfectly secure, but we take reasonable measures appropriate to the data we hold.

7. Children

The App is rated for ages 4 and up, but it requires an Apple or Google account and a sign-in, so it is not directed at children under 13. We do not knowingly collect data from a child under 13. If you believe a child has created an account, contact us and we will remove it.

8. Your Rights

You can view and edit your words and preferences directly in the App, and delete your account at any time. Depending on where you live, you may also have the right to request a copy of your data, correct it, or object to certain processing. Write to support@capdex.app and we will act on the request.

9. International Transfers

Firebase and our AI provider operate globally, so your data may be processed on servers outside your country. Those providers apply their own safeguards for such transfers.

10. Changes to This Policy

We may update this policy as the App changes. Significant changes are announced in the App, and the date above is updated.

11. Contact

Questions about privacy: support@capdex.app. We aim to reply within 15 business days.