Privacy Policy — Yayu

Last updated: 25 October 2026

Yayu shows one Chinese word a day. There are no accounts and no sign-in, nothing here is sold, and most of what the app knows about you never leaves your phone.

What the app keeps on your phone

The word list, the dictionary, the typefaces and the Mandarin pronunciation recordings all ship inside the app, so it works offline. The Cantonese recordings are an optional download: they are fetched only if you choose Cantonese pronunciation and agree to download them, and they come from the App Store or Google Play, the same as the app itself. Once downloaded they stay on your phone. So does everything it learns about you: which words you have seen, which you have hearted, where you are in the trail you have browsed, your reminder time, and your display and filter settings.

None of it is stored anywhere but your phone. There is no account and nothing is synced, so none of these lists is uploaded, and nobody can look up what you have saved. What you type into search is never sent. Deleting the app removes all of it from your phone — though if you later restore a device backup made while the app was installed, it can come back with it, the same way your other apps' data does.

That is about where your data is kept. It is not the same question as what is counted: some of these actions are also counted, and three of those counts name the word involved. Read Usage counts below for what actually leaves the phone — in particular, hearting a word is counted, and the count says which word it was.

What the app sends, and to whom

Usage counts — to us

The app counts how its features are used, so we know what to build, and sends those counts to a server we run on Cloudflare. What is counted: opening the app, moving forward or back through words, opening Settings, hearting a word, sending one to Pleco, exporting, sharing or saving a word card, playing a pronunciation (the count says whether it was in Mandarin or Cantonese, not which word), changing the pronunciation language, downloading the Cantonese recordings (whether the download started, finished or failed), opening a reminder, what became of the daily-reminder prompt, whether you allowed or refused notification permission, changing the language definitions are shown in, tapping a word's characters to change their style (the count says which style, not which word), and whether the first-time tip about that tap was followed or passed by.

For a word card, the count also says what you chose to put on it — whether the pronunciation and the translation were showing, and whether the characters were laid out as a square — and whether you shared it or saved it to your photos. It does not include the picture, and it does not say which word was on it.

Each count carries:

• An install identifier — a random value created the first time the app sends usage counts, and stored on your phone. It identifies an installation, never you. It stays the same across app launches and updates. We store it separately and mark it to be excluded from device backups. Your saved words and settings can still return from your backup.
• Your platform, device model, OS version and app version. On iPhone and iPad the model is Apple’s hardware model code rather than its marketing name.
• Whether you have a subscription, as a plain yes or no, with no purchase details.
• The language definitions are shown in — English, German, French or Japanese.
• The country the request came from, which our server reads from the connection. Never a city, and never your IP address, which is not recorded.

Three of these counts record which word it was: hearting a word, sending one to Pleco, and exporting a single word. Exporting a list records that a list was exported, not what was in it.

Hearting a word or sending it to Pleco also records its vocabulary difficulty band, including the shared advanced HSK 7–9 band. This describes the word; it does not record the difficulty filters you selected.

Every word involved comes from the dictionary inside the app, so none of it is anything you wrote — but over time that record is a picture of what you are studying, attached to the identifier for your install. There is no setting that turns this off.

Sending a word to Pleco is only possible if you have Pleco installed, so that count also tells us a Chinese dictionary app is on the phone. The app does not and cannot read the list of apps on your device.

Performance measurements on iPhone and iPad — to us

Apple's MetricKit framework measures how the app performs and combines those measurements on your phone over a daily window. We send selected totals and histograms to the server we run on Cloudflare: launch and resume time, hangs, CPU and GPU time, time in the foreground and background, disk writes, peak memory use and scrolling hitches, together with the app version.

These reports carry no install identifier, device description, country, words, usage events or crash call stacks. We store them separately from usage counts and do not combine the two. They are kept for three months, to find and fix performance problems. There is no setting that turns this off.

Crash and performance reports — to Sentry

When the app crashes or hits an error, a report goes to Sentry so the fault can be fixed. It carries the error, the trail of events leading to it, and your device model, OS version and app version. Usernames, email addresses and IP addresses are switched off, and the console trail is excluded. Nothing you were reading, searching for or had saved is part of a report.

Alongside reports, the app sends a short record of each time it runs and whether it ended normally or in a crash. Sentry's libraries may attach an identifier for the installation to those records; where it exists it identifies an installation, never you.

The app also sends a sample of startup and home-screen performance reports to Sentry: how long it takes to display the first word with its fonts, and measurements of how smoothly the screen draws. Reports include the app and device information described above and Sentry's trace/session identifiers. We configure a 10% chance of collecting each performance transaction; this does not select a permanent group of readers. These reports contain no words, searches, saved lists or usage counts, and no screen recordings or pictures. There is no setting that turns this off.

Sentry's handling of what it receives is covered by their privacy policy.

Advert requests — to Google

Yayu shows adverts in two places: a card in the feed every few swipes, and a full-screen advert on the way into Favorites. They come from Google AdMob.

• Not straight away. Neither appears to a new reader. The advert software starts only once you have used the app on enough separate days to become eligible for adverts.
• On iPhone and iPad the adverts are not personalised, which is why Yayu never asks for permission to track you across other companies' apps and websites.
• In the EEA and the UK you are asked before any advert is requested. You can change your answer under Settings → Your advert choices. Declining limits what Google may use when choosing adverts; it does not switch them off.
• There is no setting that turns adverts off, and no advert-free tier in this release.

To show an advert, the app asks Google for one. That request carries your IP address and a description of your device, and on Android your device's advertising ID, which you can reset or opt out of under Settings → Privacy → Ads. On iPhone and iPad no advertising identifier is sent. Google uses this for its own advertising business rather than on our behalf, so it is covered by Google's privacy policy and their partner-sites notice.

Nothing you read, search for, heart or export is sent to Google, and the app does not tell Google which word you were looking at. The Android app does not request interest categories inferred from your use of other apps.

Rating the app — to Apple or Google

After you have read a few words, Yayu may show a card asking whether you are enjoying it, and your phone's own rating prompt may appear over it. That prompt belongs to the App Store or to Google Play, not to us: it is the same one any app can ask for, it is limited by the store rather than by us, and we are not told whether it appeared or what you did with it. Tapping the star instead opens your store's page for Yayu.

A rating or review you leave is published by the store under your store account. It does not pass through us, we are not told which account left it, and we cannot change or remove it — that is between you and the store.

Yayu counts, on your phone only, how many words you have seen today and how many times you have swiped the card away, so that it stops asking. Those counts are never sent anywhere.

Notifications

If you turn on the daily reminder, your phone schedules it from words already on the device. There is no push server or push token, and scheduling and delivering the reminder sends nothing to a server. Opening a reminder and answering the reminder prompt or permission question are counted as described under Usage counts above.

Sharing a word

Exporting a word list or a card hands a file to your phone's share sheet. Where it goes from there is your choice; Yayu does not upload it anywhere.

Saving a card puts the picture in your own photos, or on older Android versions in a file you choose. Yayu never reads your photo library — it only writes the card you asked it to save.

Whether your phone asks you to allow that depends on the phone:

• On iPhone and iPad, you are asked once, and only for permission to add photos. Looking at your library is a separate permission that Yayu does not request and could not use.
• On recent Android versions, you are not asked at all, because adding a picture this way needs no permission.
• On older Android versions, you choose a destination with the system file picker. Only the file you choose can be written; no shared-storage permission is requested.

The picture is made on your phone from a word the app already carries, and it is not uploaded anywhere either.

What does leave the phone, for a share or a save alike, is the count described under Usage counts above — that it happened, what was on the card, and which of the two you chose. Never the picture, and never the word.

The identifiers

The app's own install identifier, any identifier Sentry attaches and Google's advertising ID are separate values held by separate services. We do not join any of them to any other, and none is linked to your name, your email or an account — there are none to link to.

Deleting the app removes our own install identifier. We mark it to be excluded from device backups. Identifiers managed by other services can have different lifetimes. Your advertising ID belongs to your phone, is shared with other apps that request it, and outlives this one. Reset or opt out of it under Settings → Privacy → Ads on Android; on iPhone and iPad Yayu never receives it at all.

What Yayu does not do

• No selling of data to anyone. Apart from Google's part in showing adverts, the services above act for us, on our instructions.
• No advertising identifier on iPhone and iPad, and no tracking anywhere — which is why the app never asks permission to track you.
• No access to your device's location, contacts, microphone or camera, and no reading of your photos — saving a card can add one, and that is all it can do.
• No third-party trackers beyond the advert request described above.

Children

Yayu is not directed at children and does not knowingly collect personal information from anyone, children included.

Changes

If this policy changes, the date at the top changes with it.

Contact

Questions about this policy, or about anything above: Yayu.daily.chinese@gmail.com