Chăm Luyện

Last updated 12 October 2026.

The short version

Chăm Luyện has no ads, no analytics and no tracking, and there are no purchases in the app. Without an account, nothing about your child leaves the device except downloads of voice files. Signing in to an account, which we create for a grown-up on request, adds the few things listed below and nothing more.

What goes over the internet

Voice files. One voice comes with the app. The others are downloaded from the app's public page on GitHub (github.com/azun-k2/chamluyen), when your child picks one, a couple of minutes after the app opens, when Settings is opened, and when the app goes to the background. Each download asks for a sound file by its name; it carries no information about your child, their progress or their name.

What GitHub sees. Like any website, GitHub receives your device's IP address and the usual details of a web request when a file is downloaded. GitHub handles that under its own privacy statement. We receive nothing from these downloads.

Checked before use. Every downloaded voice is checked against a fingerprint built into the app, and is discarded if it does not match.

Your account, only when you sign in. There is no sign-up in the app: we create the account for a grown-up on request. Our server (Cloudflare Workers and a Cloudflare D1 database) then holds the phone number, the parent's name if given, a salted hash of the password (never the password itself), the plan records (package, start and end dates), the devices that are signed in (a device name such as "iPhone" and when it was last used) and the date of the last sign-in. It is used only to sign in, to know whether a plan covers today, and to help you when you write to us. It is not sold, not shared for advertising, and not used for analytics or tracking.

The national board, only with an account that has a plan. The app sends your child's best score in each break game together with the name typed in the app. Other children see that name, the score and the last four digits of the account's phone number, so two children with the same name can be told apart. Names are checked on our server, and an unsuitable one is shown as "Bạn nhỏ". Nothing else about your child's progress is sent.

What is stored, and where

Your child's profile, on the device: the name typed in, the buddy, stars, progress and settings, kept in the app's own storage. A small copy of the progress is also kept in the device's Keychain, so that installing the app again does not lose it; it stays on the device and is not sent to us. If your device backs itself up, for example to iCloud, the backup can include the profile, as it does other apps' data.

Downloaded voices are kept in a separate folder that is left out of backups, since they can be downloaded again.

Deleting the app removes the files; the small Keychain copy stays on the device for a reinstall.

Deleting an account. A signed-in grown-up can delete the account in Settings with the password. That removes the phone number, name, plan records, signed-in devices and board scores from our server. Our back-office activity log may keep a short record of staff actions (who, what, when) that refers to the account.

Feedback email

If a grown-up taps Góp ý cho người làm ứng dụng in Settings, the app opens a new email in your mail app with a short template: the app version, the device model and iOS version, the chosen accent, whether the voice is on, and the number of stars. Nothing is sent until you press Send, and you can change or delete any of it first.

Children

Chăm Luyện is made for children. It asks only for a first name, so the buddy can greet the child; that name stays on the device unless a signed-in account is on the national board, as described above. Children do not create accounts, and there is nothing to buy in the app. Everything the child hears was written and recorded in advance; no AI talks to your child.

Contact

Questions about this policy, or anything else: support@khangazun.com.