Privacy Policy

Koi Kioku — Japanese learning app by Onebuzz. Effective: July 16, 2026

The short version

Your learning data stays on your device. We don't run analytics on your behavior, we don't track you across apps, and we can't see what you study.

What stays on your device

All flashcards, decks, review history, streaks, and study progress are stored locally on your device. They are never uploaded to our servers. If you delete the app, this data is deleted with it.

What we receive

• A random identifier. The app generates a random ID (UUID) that is attached to your App Store purchase and, if you arrived through a partner link, sent once to record that referral. It is not linked to your name, email, or any other identity — we don't collect those at all.
• Subscription status. Apple notifies our server when a subscription starts, renews, expires, or is refunded, so Pro features work. Payment details never reach us; they are handled entirely by Apple.
• AI feature inputs (Pro only). When you use AI deck generation or Ask Anything, the topic or question you type is sent to our server and processed by our AI provider (Anthropic) to generate the response. On devices that support on-device AI, questions are answered on your device and never sent to us. We apply monthly fair-use limits and keep usage counts, not the content of past requests.
• Crash reports. If the app crashes, a technical crash report may be sent so we can fix bugs. Crash reports are not used to track you or measure your behavior.

What we don't do

• No advertising SDKs, no behavioral analytics, no fingerprinting.
• No tracking across other companies' apps or websites (we don't use the IDFA).
• No selling or sharing of personal data.

Data retention

The random identifier, subscription status, referral record, and fair-use counters are kept while needed to operate the service. You can request deletion by contacting us with your device (the ID is shown nowhere, so simply deleting the app and letting your subscription lapse effectively orphans the record; contact us if you want it removed sooner).

Children

Koi Kioku is not directed at children under 13 and does not knowingly collect personal information from them.

Changes

If this policy changes, the updated version will be posted at this URL with a new effective date.

Contact

Questions or deletion requests: support@onebuzz.net