Privacy policy

This policy explains what OptimalChinese collects, why, who else sees it, and what you can do about it. It is written to be read, not to be survived.

Who is responsible

BrightPath Learning, 19 rue de la Victoire, 38400 Saint-Martin-d'Hères, France — the data controller for everything described here. Questions, requests, complaints: contact@optimalchinese.com.

What we collect

Your account — your email address, your first name, and your password (which is stored hashed; nobody here can read it). If you sign in with Google or Apple instead, there is no password. Google or Apple gives us your email address, your first name if you share it, and the identifier of your account with them. With Apple's Hide My Email, the address is a private one that forwards to yours. The sign-in itself happens on their side, under their own privacy policies. For Apple we also keep the token it issues, so that deleting your account also ends this app's access at Apple.

What you told us when you signed up — why you are learning Chinese, roughly what level you are at, what you have used before, your goal, and how many minutes a day you want to study. This is what builds your plan.

Your learning data — the words and rules you study, every review and how it went, your settings, your notes, anything you add or import yourself, and the collections you build. This is the bulk of it, and it is the part the service exists to keep.

Your classroom, if you use one — the list you and your teacher build together. A teacher joining by your link has no account: we store an anonymous session identifier and when they were last active, and nothing that identifies them.

Messages you send us — through the contact or bug-report forms, or Send feedback inside the app: your name if you give it, your email, and what you wrote. A bug report or feedback from inside the app also attaches technical details, because a report without them is usually unactionable: the app version, your device and browser, your screen size and language, the page you were on, and — from inside the app — whether your device was in sync with your account (how many changes were still waiting to sync, and the last sync error).

Your subscription — whether you have one, which plan, and the identifiers Stripe gives us to look it up. We never see your card number. It goes from your browser to Stripe and never passes through us.

Technical records — our host keeps standard server logs (IP address, browser, which page was requested) and we keep short-lived counters that stop one account from overloading the AI.

We do not sell your data. We do not use advertising trackers. We have no interest in your data beyond running the thing you paid for.

Why we are allowed to hold it

Every purpose, with the legal ground under the GDPR that permits it:

Who else sees it

These are the companies that process data on our behalf. They may use it only to do the job listed and nothing else.

Data that leaves Europe

Some of those providers are outside the European Economic Area. For providers in the United States we rely on the European Commission's Standard Contractual Clauses, and on the EU–US Data Privacy Framework where the provider is certified under it.

One transfer deserves to be called out plainly: the AI that writes your example sentences and answers you in the tutor runs in China, and there is no European adequacy decision for China. Anything you type into the AI tutor is sent there. We make that transfer because it is necessary to provide the service you signed up for. If you would rather nothing you write reached China, do not use the AI tutor — every other part of the app works without it.

How long we keep it

Your account and learning data — for as long as your account exists. Delete your account and it goes with it, immediately and for good.

Backups — we keep restore points so a mistake is recoverable: the last seven days, then one a week for about two months. They age out on their own.

Billing records — ten years, because French accounting law requires it. This is the one category that survives deleting your account, and it is invoices, not learning data.

Messages, bug reports and feedback — up to three years, so a long-running problem still has its history.

Server logs and rate-limit counters — days, not months.

What you can do about it

You have the right to see your data, correct it, take it elsewhere, have it deleted, restrict or object to what we do with it, and withdraw any consent you gave.

Two of those need no email from you: export gives you everything the account holds as one file, and delete removes it — both from your account page. For anything else, write to contact@optimalchinese.com and we will answer within a month. The deletion steps are also written out, with what goes and what stays, at optimalchinese.com/delete-account.

If you think we have got this wrong, you can complain to your national data-protection authority. Ours is the CNIL, 3 place de Fontenoy, 75007 Paris, France — cnil.fr.

Cookies and what is stored on your device

Cookies we cannot do without. Signing in sets a cookie that keeps you signed in. Without it there is no account, so it is exempt from consent and there is no way to refuse it and still use the service.

Your learning data, on your device. The app keeps a full copy of your dictionary and study data in your browser's storage so it works offline and opens instantly. It never leaves your device except to sync with your own account, and deleting your account wipes it.

On the website, analytics only if you say yes. If you accept, PostHog collects three things, on servers in the European Union: which screens you use and what you click; a recording of your session — the pages you moved between and where you hesitated; and any error the app throws, so we can fix it.

Because a recording is a far bigger thing than a page count, two rules are built into it and are not settings you have to trust us about. Nothing you type is ever recorded — every input is masked in the browser before anything is sent, so your email, your password, your notes and your messages to the tutor never leave your device as part of a recording. And your conversations with the AI tutor are masked entirely, both what you write and what it answers. What a recording shows is where you went and what you pressed.

If you refuse, nothing is loaded at all — not a disabled tracker, nothing. You can change your answer whenever you like from Cookie settings at the bottom of any page of the website.

The iPhone, iPad and Android apps collect no analytics at all. They never load PostHog and never ask, so the only cookie they set is the sign-in one above. Nothing anywhere in OptimalChinese tracks you across other companies' apps or websites.

If you are under 18

You must be at least 13 to have an account. If you are under 18, a parent or guardian has to agree to the Terms for you and be the one paying. If you believe a child has an account they should not have, write to contact@optimalchinese.com and we will remove it.

Decisions made about you by a computer

None that have any legal effect. The scheduling algorithm decides when to show you a card. That is the whole of it.

Keeping it safe

Data is encrypted in transit and at rest, access to the database is restricted per account at the database itself, and the parts of the service that spend money refuse requests that are not authenticated. No system is perfect; if something goes wrong that affects you, you will hear it from us.

Changes

If this policy changes in a way that matters, we will tell you by email before it takes effect. Small corrections happen on this page.