Delta
Privacy Policy
Last updated 14 September 2026
Delta is a daily learning app for AI and machine learning engineers. This policy describes exactly what the app collects, why, and who else sees it. It is written to match what the code actually does.
Delta shows no advertising and does no tracking. There is no advertising identifier anywhere in the app, no analytics SDK, no data broker, and nothing about you is combined with data from other companies' apps or websites.
What is collected
| Data | Why |
|---|---|
| An anonymous account identifier | Created automatically on first launch. You are not asked for anything to get one. It exists so your progress and your free allowance survive across sessions. |
| Your answers — which card, whether the answer was correct, how long it took, and when | Delta schedules what you see next based on what you have already learned and how confidently you recalled it. The timing matters: a correct answer that took twelve seconds means something different from one that took two. |
| Purchase status | Whether you hold an active subscription, so the app knows what to unlock. |
That is the complete list. Delta does not ask for or collect your name, email address, phone number, contacts, photos, location, health data, or browsing history.
Sign in with Apple
If you choose to sign in with Apple, Delta receives only the identifier Apple provides. Apple lets you hide your email address, and Delta works fully either way. Signing in links your existing anonymous progress to that account so you keep it on a new device. You can use Delta without ever signing in.
What stays on your device
Your streak, your display preferences, and your login token are stored on your device only. The login token is held in the iOS Keychain. None of this is transmitted anywhere.
Who else sees it
Delta uses two service providers, and no others:
- Supabase hosts the database and handles sign-in. It stores the anonymous account identifier and your answer history on our behalf. Supabase privacy policy.
- RevenueCat manages subscriptions. It receives an app-specific identifier and your purchase status from Apple. It never receives your answers or anything you learn. RevenueCat privacy policy.
Payments are handled entirely by Apple. Delta never sees your card details, billing address, or Apple ID.
Nothing is sold, rented, or shared for advertising. Data is disclosed to anyone else only if the law compels it.
Card content and "Go deeper"
Cards are written in advance and are the same for everyone; generating a card does not involve your data. When you tap "Go deeper", the request sent to the language model contains the card's own text and nothing about you. Those expansions are cached and shared across all readers.
How long it is kept
Your answer history is kept while your account exists, because it is what the scheduler runs on. Delete your account and it is deleted with it.
Your rights
You can ask for a copy of your data, ask for it to be corrected, or ask for it to be deleted entirely. Email drvncrypto@gmail.com and we will action it within 30 days. Deleting the app alone does not delete server-side data; ask us and we will remove it.
If you are in the EEA or UK, the legal basis for processing is performance of the contract — you cannot have a learning app that adapts to you without a record of what you have learned. If you are in California, Delta does not sell or share personal information as the CCPA defines those terms.
Children
Delta is built for working engineers and is not directed at children under 13. We do not knowingly collect data from them. If you believe a child has provided data, contact us and it will be deleted.
Security
All traffic uses HTTPS. Database rows are protected by row-level security, so an account can read only its own records. Credentials on your device live in the iOS Keychain.
Changes
If this policy changes materially, the date at the top changes and the app will say so before the change takes effect.