Summary
CHAC works fully without an account. The app stores your learning progress locally on your own device. You can optionally sign in to carry that progress to another device, and only then does VOGTOV receive a copy of it. Signed-in learners can also choose whether to receive occasional CHAC updates by email. That choice is off by default and can be changed in Profile. The free version shows ads supplied by Google AdMob, and optional in-app purchases remove those ads. Google's advertising software collects a device advertising identifier in order to serve and measure ads. Apple or Google and RevenueCat process purchase and entitlement information for an ad-free plan; CHAC never receives your payment-card details.
Information CHAC stores
CHAC stores lesson and review progress, character mastery, streak and scheduling information, and related learning preferences in the app's local storage on your device. If you are not signed in, this information is not linked to an account and does not leave your device.
Accounts and sync
Signing in is optional. Every learning feature works without it, and the app can be used indefinitely with no account at all.
If you choose to sign in with Google or Apple, CHAC receives an account identifier and any email address or name that provider supplies, and stores them through Google Firebase Authentication. It does not receive your Google or Apple password.
While you are signed in, CHAC also stores a copy of your learning progress in Google Cloud Firestore under your account identifier, so that it can be restored on another device. That copy contains the same learning information described above: streak, per-character mastery and review counts, review scheduling, a short recent-review history, and which chambers you have completed. It also stores whether you opted in to CHAC updates and the time and source of that choice. It contains no messages, contacts, photos, audio, or location.
This information is used to provide the account, sync and preference features. It is not sold, not shared with advertisers, and not used to build advertising profiles. Signing in never replaces the progress already on your device: the two are merged.
Optional CHAC updates
The email-updates switch in Profile is optional and off by default. The current app records your choice with your signed-in account and keeps a separate server-only audience record so a future delivery service can use the consent safely. No email delivery service is connected yet, so opting in does not currently send messages. If CHAC begins sending updates in a future version, you will be able to opt out from the same preference and every marketing message will include an unsubscribe option.
Advertising
CHAC is free and is funded by advertising. Ads are supplied by Google AdMob. To select and measure them, Google's Mobile Ads SDK collects a device advertising identifier, information about how you interact with an ad, and basic diagnostic information about the app. That information goes to Google and its advertising partners. It does not go to VOGTOV, and your learning progress is never shared with advertisers.
On iPhone and iPad, CHAC always requests non-personalised ads. It shows no App Tracking Transparency prompt and does not track you across other companies' apps or websites.
On Android, where local rules require it, CHAC asks for advertising consent through Google's User Messaging Platform before requesting ads, and follows the choice you make there. Your device settings also let you reset your advertising identifier or opt out of ad personalisation at any time.
Ad-free purchases
CHAC offers monthly and yearly auto-renewing plans, plus a lifetime one-time purchase, to remove advertising. Purchases are completed by Apple or Google through the store account on your device and are tracked by RevenueCat so CHAC can restore the ad-free entitlement. You can restore purchases or manage a recurring plan from Profile in the app. Store receipts, billing details, refunds and cancellations are governed by the relevant store's policies; VOGTOV does not receive your payment-card details.
Information CHAC does not collect in this version
CHAC does not collect payment-card details, run its own payment processor, run a separate analytics or crash-reporting service of its own, collect your contacts, request photos, microphone or camera access, or request your location. It never asks for or receives your Google or Apple password.
Children
CHAC is intended for a general audience and is not directed to children. It is not part of a families or kids programme on either app store.
Pronunciation
CHAC may use the operating system's text-to-speech capability to play a Chinese pronunciation. CHAC does not record your voice and does not send audio to VOGTOV for this feature.
Website contact
If you email support, VOGTOV receives the information you choose to include in that email so it can respond to your request. Support correspondence is handled through the email service used for the VOGTOV address.
Deleting your account and data
If you signed in, you can delete your account from inside the app: open Profile and choose Delete account. This deletes the synced copy of your learning progress, the email-updates choice, its internal audience record and the account itself. The progress saved on your device stays, so you can carry on learning offline.
Deleting the app removes its local app data. On iPhone or iPad, choose Delete App, not Offload App, if you want to remove the app and its local data. Device backups may retain a copy until your backup provider removes or replaces it.
The advertising identifier described above belongs to your device rather than to CHAC, so it is not removed by deleting the app. You can reset or delete it in your device's privacy settings.
Changes and contact
CHAC may change as it develops. If a future version adds materially different data collection, starts sending updates, or adds another sign-in provider, this policy will be updated before or with that release. Questions can be sent to pim@vogtov.com.