Privacy Policy — Chiong Lab
Chiong Lab is a free O-Level physics practice app. This policy says what we collect, why, and how you can get rid of it. We do not sell data and we do not show ads.
Who this is for
Chiong Lab is built for secondary-school students preparing for O-Level, IGCSE and GCSE examinations in physics. You must be 13 or older to create an account.
You can practise as a guest with no account. Guest progress stays on this device and is not sent to our servers.
What we collect when you create an account
Name, email address, and a password. The password is stored only as a one-way hash (scrypt). We cannot read it back.
If you sign in with Google, Google gives us your name, email and profile picture. If you sign in with Apple, Apple gives us your name and an email address — which may be a private relay address that forwards to you, and we are happy with that. We never receive your Google or Apple password.
A session token so you stay signed in. On a phone this is stored on the device; on the website it is stored in a first-party cookie.
What we collect as you practise
Learning record: XP, streaks, freeze tokens, lesson completion, answers and Leitner boxes, daily and weekly activity, quests and achievements.
Your notebook: the questions you got wrong, and any question you chose to save, so you can go back to them.
If you rate a question, or a card in a lesson, we store that rating — and any note you choose to add to it — against your account so we can find the questions and lesson cards that are not good enough and rewrite them. Rating and the note are both optional, nothing asks you twice, and changing your mind replaces the old rating rather than adding to it.
Optional public profile: if you turn “Public profile” on, classmates who are signed in can search for your name or handle and see your stats. Profiles are private until you opt in. We do not publish a public directory of every student.
If you join a league, your weekly XP and display name are shown to the other real students in that week’s board.
What you write, and who sees it
With an account you get a feed. It shows milestones — a streak, a cleared day of quests, a league finish, an achievement — for you and for students you have accepted as friends. The posts are generated from your own record; you do not write them.
You can write comments of up to 300 characters on those posts, react to them, and tag a friend by their handle. Comments are stored on our servers. They are visible only to the author of the post and to their friends, and are never public, never indexed by search engines, and never shown to a signed-out visitor.
Display names, handles and comments are all checked against a word filter before they are saved. Anything that matches is refused.
When you tag someone we store who you meant, so the tag can open their profile later even if they change their handle.
Reports and moderation
You can report a student from their profile, and you can report a single comment from the comment itself. A report records who filed it, the reason, anything you typed, and the account it is about.
A report about a comment also stores a copy of that comment as it was written. That copy stays if the comment is later deleted — by its author or by the person whose post it sat under — because a moderation record that disappears the moment somebody has second thoughts is not a moderation record.
Moderation records outlive account deletion. If you delete your account we erase your identity and your learning record, but a report filed about you keeps the words that were reported and the fact that they were reported. It does not keep your email, your password, your progress, or anything else about you.
A person reads every report.
Notifications
If you turn reminders on, we store a notification token for that device so we can send the daily practice reminder and occasional announcements about the app. Turning reminders off, signing out, or deleting the account removes the token.
We do not use notifications for advertising, and we do not sell or share the token.
Classes
If you join a class with a code from a tutor, the tutor who owns that class can see your display name and how ready you are for each chapter. They cannot see your email, your password, your friends or your feed.
Leaving the class ends that access. Joining is always your action — nobody can add you to a class without the code.
What we do not collect
We do not collect precise location, contacts, payment details, or advertising identifiers. We do not read your camera roll.
We do not use third-party analytics SDKs or advertising networks. There are no ads in the app.
The app contains a crash reporter, and it is switched off in the shipped build: no reporting endpoint is configured, so no diagnostic data is collected or leaves your device. If that ever changes, this policy and the App Store privacy label change with it, in the same release.
We do not sell, rent or share your personal information for advertising.
Sharing a picture
If you tap Share on a streak, a record or an achievement, we paint a PNG of it on your device and hand that file to your phone’s own share sheet. What happens next is your phone’s business: you pick Messages, Instagram, Save Image, or you cancel. The file is written to a temporary folder and we do not upload it or keep a copy on our servers.
We ask for no photo-library permission, and the app cannot read your camera roll. Saving the picture, if you choose to, is done by the operating system under a permission you grant it rather than us.
How we use the data
To keep your progress, sign you in on another device, mark questions, run weekly leagues, show your friends’ feed, and (only if you opt in) let classmates find your public profile.
To operate, secure and improve the service — for example rate-limiting logins, filtering names and comments, and deleting unused sessions.
We do not use your learning record to train public AI models.
Who else sees it
Your data is stored on our hosting providers (the app server and its database). They process it only to host the service.
Google or Apple sees a sign-in request if you choose one of them. That is their privacy policy, not ours.
Other students see only what you make public, your display name and weekly XP on a league board you join, and — if they are your friends — your milestones and anything you have written in a comment.
A tutor sees your name and chapter readiness for a class you chose to join.
How long we keep it
Account and learning data stay until you delete the account.
Guest play is not uploaded. Clearing the app, or Reset all progress, erases the copy on that device.
Session tokens expire. Login-attempt logs are kept only long enough to stop password guessing.
Moderation records are the one exception, and are described under Reports and moderation above.
Your choices
Download everything we hold about you: MORE → Your data. It arrives as a file you can keep.
Delete account: MORE → Delete account. That erases your identity, sessions, progress on the server, onboarding answers, attempts, notebook, ratings, league seats, friend links, feed posts and comments. Progress on this device is a separate copy; Reset all progress erases that. Moderation records are the exception described above.
Delete a single comment you wrote at any time, from the comment itself.
Make your profile private at any time on your Profile page. Search will stop returning you.
Log out. The server account remains; this device forgets the session.
Practise as a guest and never create an account.
Children
You must be 13 or older to create an account. We do not knowingly collect personal information from children under 13. If you believe we have, email us and we will delete it.
Profiles default to private so a classmate cannot look someone up unless that person chose to be found, and comments are limited to students who have accepted each other as friends.
Security
Passwords are hashed. Production traffic uses HTTPS. Access tokens are short-lived; refresh tokens rotate.
No method is perfect. Do not reuse a password you use on other sites.
Changes
If this policy changes in a way that matters, we will update the date at the top (currently 9 September 2026) and keep the in-app copy under MORE.
Contact
Questions, or a request to delete your account without opening the app: hello@chionglab.com. Write from the address the account uses and say which account you mean. You can also delete it yourself in the app under MORE.