Privacy policy

Last updated: 20 October 2026

In short: 放心 (fàngxīn, "rest assured", literally "let go of the heart"). Your words, lists, reviews and settings stay on your phone. Zìzài has no account, no ads and no analytics, and we never see what you study. A few things involve Google; this page lists each of them.

Who we are

Zìzài 字在 is made by one person:

David Medenjak
Austria
davidmedenjak+zizai@gmail.com

"We" and "us" on this page mean David Medenjak, the controller under the EU General Data Protection Regulation (GDPR). Questions about this policy or your data go to the email address above.

This policy covers the Zìzài Android app and this website.

What stays on your phone

Your study data (the lists you picked or made, your cards, your reviews and your settings) is stored on your phone, in the app's private storage. The dictionary and the HSK word lists come with the app and hold nothing about you.

We have no server that receives any of this. Studying works offline, and we can't see, change or delete your data, but you can (see Your data). Uninstalling Zìzài deletes it, unless you choose to keep it when Android asks.

Read aloud uses your phone's own offline voices. Zìzài never listens: it has no access to your microphone.
Your phone schedules the daily reminder itself.
The What's due widget shows how many words are due and when the next ones are, never a word or an answer. It sits on your home screen, so anyone who sees your screen sees it too.
Export, share, import and Open in Pleco only hand words to the app or file you pick. Zìzài reads the clipboard only when you tap to add words from it.

Your data: copies, restore and delete

In More → Your data you can save a copy of your study data as a .zizai file, restore from one, or delete everything.

A copy goes only where you save it, using your phone's file picker. If you pick a cloud drive, that provider stores it under its own terms. The file holds your study data plus when it was made, Zìzài's version and how many words, lists and reviews it holds; nothing that identifies you.
Opening a .zizai file never restores it by itself; Zìzài asks first.
When you restore or delete all, your previous data stays on your phone for 30 days so you can undo it, then it's deleted.
Clearing Zìzài's storage in Android's app settings opens Your data, so nothing is lost by accident.

Google Play and Zìzài Plus

Zìzài Plus is an optional monthly subscription, sold through Google Play.

When you open Zìzài, it asks Google Play whether you support Plus, so Plus follows you to a new phone. The answer (whether it's active and renews) is kept on your phone.
If you subscribe, Google handles the purchase and the payment; we never see your payment details. Google gives us the order details we need for accounting, taxes and refunds.
Google's billing library inside the app sends Google technical information about these checks and purchases.

Legal basis: the contract with you (Art. 6(1)(b) GDPR), our legal obligations to keep order records (Art. 6(1)(c)), and our legitimate interest in recognising supporters without an account (Art. 6(1)(f)). Order records are kept as long as Austrian tax law requires. Google processes this data under the Google Play Terms of Service and its privacy policy.

Fonts from Google

Some fonts are downloaded from Google Fonts through Google Play services. The request names the font, nothing about you or your studies; like any download, Google sees your IP address.

Legal basis: our legitimate interest in an app that looks right without a bigger download (Art. 6(1)(f) GDPR).

Android backup

Zìzài lets Android back up your study data and settings with your phone's backup, so a new phone picks up where you left off. It only happens if backup is on in your phone's settings, and we never receive the backup.

Legal basis: our legitimate interest, and yours, in not losing your progress (Art. 6(1)(f) GDPR).

Crash reports (optional, off unless you turn them on)

If you turn on Send crash reports (on the welcome screen or in More → Privacy), Zìzài sends us a report when it crashes, through Firebase Crashlytics, a Google service. A report contains what went wrong in the code, your phone model and Android version, Zìzài's version, and random IDs for the installation and the app session. It never contains your words, lists, reviews or settings.

While crash reports are on, Zìzài also tells Crashlytics each time it starts, with the same IDs, phone model and versions and nothing else, so we can see how often it runs without crashing.

Nothing is sent before you turn crash reports on, and crashes from before that are deleted, not sent. You can turn them off any time in More → Privacy.

Legal basis: your consent (Art. 6(1)(a) GDPR, § 165(3) of the Austrian Telecommunications Act 2021). Turning it off withdraws consent for the future. Google processes the reports for us as our processor; Crashlytics deletes them after 90 days.

Google Play statistics

Like for every app on Google Play, Google gives us install statistics and, if you allowed your phone to share diagnostics with Google, crash reports (Android vitals), aggregated or without anything that identifies you.

This website

This website is hosted on Cloudflare Pages (Cloudflare, Inc., USA), which processes your IP address to deliver it. It sets no cookies and uses no analytics.

Legal basis: our legitimate interest in publishing this page (Art. 6(1)(f) GDPR).

Transfers outside the EU

Google and Cloudflare may process data in the USA. Both take part in the EU-U.S. Data Privacy Framework, for which the European Commission decided that the USA ensures an adequate level of protection (Art. 45 GDPR).

Your rights

You have the right to access, correct or erase your data, to restrict or object to its processing, to data portability, and to withdraw your consent any time (Art. 15–21 and 7(3) GDPR). We hold very little about you; your study data is on your phone, not with us. To use these rights, email us.

You can also complain to the Austrian Data Protection Authority (Österreichische Datenschutzbehörde, dsb.gv.at).

Children

Zìzài doesn't ask for anyone's age and doesn't knowingly collect data about children. If you're under 14, please ask a parent before you turn on crash reports.

Changes

When Zìzài changes what it does with data, this policy changes first, and the date at the top changes with it. If a change needs your consent, the app asks before anything is sent.