Privacy Policy for Octo

Last updated: 3 September 2026

Octo ("Octo", "the app", "we", "us") is a flashcard app that imports Anki decks and schedules reviews. This policy explains what data the app processes, why, and who it is shared with. It is written to satisfy the EU General Data Protection Regulation (GDPR) and Apple's App Store requirements.

Controller (responsible for your data under GDPR Art. 4(7)):

Peter Dominik Nils Lukas Schaefer
Röbbek 4
22607 Hamburg
Germany
Email: peterschaefer444@gmail.com

The short version

Octo is built to keep your data on your device. Your decks, cards, review history and settings never leave your phone unless you ask for one specific optional feature, a word note written by an AI model. We do not require an account, we do not use analytics or advertising SDKs, and we cannot see your cards.

1. Data stored only on your device

Everything you create or import in Octo is stored in a local database on your device and is not transmitted to us or anyone else:

• Imported decks and cards (from the .apkg files you open), including any media inside them
• Your review history and spaced-repetition (FSRS) scheduling state
• Daily goals and statistics
• App settings (e.g. day-rollover hour, notification preferences, the language you read explanations in)
• The language Octo detects for each deck, worked out on your device from the cards' script and common words; you can change it in the app

We have no server that stores this content and therefore no access to it. If you delete the app, this data is deleted with it.

2. Anonymous install identifier

The first time you run Octo, the app generates a random identifier (a UUID) and stores it on your device. It is not linked to your name, email, Apple account, or any other personal information, and by itself identifies only this one installation.

This identifier is sent to our servers only in the two situations below (word notes and subscriptions), where it is used to apply usage limits and to match your subscription to your device. Reinstalling the app generates a new identifier. The app shows it under Settings › About so you can quote it in a data request.

• Purpose: abuse/rate-limit protection and linking your subscription to your device without an account.
• Legal basis: our legitimate interest in preventing abuse of the free service (GDPR Art. 6(1)(f)) and, for the subscription link, performance of a contract (Art. 6(1)(b)).

3. Word notes (optional, at your request)

Octo can write a short note about a word: why it means what it means, what it is built from, a way to remember it, an example sentence. The note is written by an AI model and is labelled as such in the app. Nothing is sent until you ask for a note. The first note in every deck is a tap on "Write the note". Once you have asked for a note in a deck, Octo writes the notes for the next lesson's words in that deck ahead of you, so they are ready when you meet the words. Decks in which you never ask for a note never send anything.

• What is sent: for the one word in question, the text of that card as your deck holds it: the headword, its reading, its translation, an example sentence if the deck has one, and similar words the deck lists; the name of the language you are learning and the language you read in; and two numbers local to your device (the deck's and the card's row ids) so the free allowance can be counted without an account. We never send your whole collection, your review history, or any identifier beyond the anonymous install id described above.
• Where it goes: the app sends this to our processing service, a stateless Cloudflare Worker operated by us, which forwards it to OpenAI to write the note. OpenAI processes the text to produce the note and returns it.
• What is stored: the note is stored on your device, once, and kept. Our Worker does not store the content of your cards or the notes; it keeps only anonymous counters keyed to the install id: daily request counts and, per deck, which card ids have received a free note.
• Legal basis: performance of the feature you requested (GDPR Art. 6(1)(b)), activated by your request for a note in that deck.

4. Subscriptions (Octo Pro)

Octo offers an optional paid subscription. Payments are handled by Apple through the App Store; we never see or receive your payment card details. Subscription state is managed through RevenueCat, which records your subscription status against the anonymous install id so the app knows whether you are subscribed.

• What is processed: your purchase/subscription status and the anonymous install id. The actual payment is processed by Apple under Apple's own privacy policy.
• Legal basis: performance of the subscription contract (GDPR Art. 6(1)(b)).

5. Notifications

If you enable reminders, Octo schedules local notifications on your device. No push token or notification data is sent to us or any third party; remote push is disabled in the app.

6. What we do NOT do

• No user accounts or logins.
• No third-party analytics, tracking, or advertising SDKs.
• No selling or sharing of personal data for advertising.
• No collection of your contacts, location, photos, or browsing history.

7. Recipients and international transfers

Depending on the features you use, the following processors may receive the limited data described above. Some are located in the United States; such transfers are covered by the EU–U.S. Data Privacy Framework and/or the European Commission's Standard Contractual Clauses.

8. Retention

• On-device data: kept until you delete it in the app or uninstall the app.
• Notes proxy: no card content or notes are retained; anonymous daily counters expire automatically (within about 48 hours). A per-deck list of card ids that received a free note, tied to the install id (no card content), is kept to enforce the free allowance.
• Subscription records (RevenueCat/Apple): retained for as long as needed to administer the subscription and meet legal/accounting obligations.

9. Your rights

If you are in the EU/EEA or UK, you have the right to access, rectify, erase, restrict, and port your personal data, and to object to processing. Because most of your data lives only on your device, you can exercise access and erasure directly by using the app or deleting it. For the limited server-side data tied to your install id, contact us at peterschaefer444@gmail.com and provide your install id (Settings › About) so we can act on the request.

You also have the right to lodge a complaint with a supervisory authority. In Germany this is the data protection authority of your federal state (or the authority competent for the controller). See: https://www.bfdi.bund.de/DE/Service/Anschriften/Laender/Laender-node.html

We do not carry out automated decision-making that produces legal effects concerning you.

10. Children

Octo is not directed to children under 16. We do not knowingly collect personal data from children.

11. Changes to this policy

We may update this policy as the app evolves. Material changes will be reflected by an updated "Last updated" date and, where appropriate, an in-app notice.

12. Contact

Questions about this policy or your data: peterschaefer444@gmail.com.