Privacy Policy

Catglish is built and run by YUE WANG, an independent developer based in the People's Republic of China. There is no company and no team — when this page says “we”, it means one person.

That is worth knowing for a practical reason: your data is handled by one individual and the providers listed below, and nobody else. For anything in this policy, including a request to delete your data, write to [email protected].

• We store the words you look up, because that is the vocabulary list — it is the product.
• We store daily totals of how much you read. We do not store which pages you read them on.
• When you press Save on a page, we keep that page’s address and title in your saved list, until you delete it.
• When you ask for a sentence translation, that sentence is sent to an AI model run by DeepSeek, in mainland China. We do not keep a copy.
• We do not sell your data, and we do not use it for advertising.

The extension only acts on a page when you turn it on for that page, from the toolbar button or the right-click menu. It is not running in the background on every site you open.

When you do turn it on, it reads the article text in your browser to find the English words on the page and underline the ones worth learning. That text is processed locally. What leaves your browser is limited to:

• the list of individual words on the page, so we can return their definitions and your review status for each;
• a word you click, to look it up;
• a sentence or phrase you select and ask to have translated;
• the address and title of the page, only when you press Save to keep it in your saved list.

Installing the extension does not give it access to every website. It asks you for access one site at a time, and only when you choose to have Catglish switch on automatically on that site; you can take that access back at any time in Chrome’s extension settings. The full text of a page is never sent to our servers. Its address and title are never sent or stored either, unless you press “Save” to keep the page, or “Send report” on a page Catglish could not read (see below).

The reading statistics are built from day-level totals only. Apart from the two exceptions described below, there is no column anywhere in our database for any of the following, so there is nothing to hand over, leak or subpoena:

• The address (URL) of any page you read
• The domain or title of any page you read
• The text of any page you read
• The time of day you read anything — reading totals are per calendar day. The one finer record is the time of each word lookup, kept at most 100 days (see the table above)
• Your location, or any device fingerprint

Both exceptions are pages you hand us yourself, one at a time.

The first is a page you save. When you press “Save” in the extension, we keep that page’s address and title, and when you saved it, in your saved list. Before it is stored, login details, the part after “#” and tracking parameters (such as utm_source) are removed from the address. We do not keep the page’s text. Our app has no screen that lets anyone but you browse your saved list. You can edit or delete any saved page on the Saved Pages page of catglish.com, and it is kept until you do. Pages you only read, without pressing “Save”, are not recorded anywhere on our side: your browsing history is never uploaded.

The second is a report you send yourself. When Catglish cannot process a page, the extension offers to send us that page's address. It shows you exactly what would be sent, and sends nothing unless you press "Send report". The address is cut down to the site and path — no query string, no fragment, no login details — and parts of the path that look like personal identifiers, such as an email address or a long token, are replaced with a placeholder. We keep it, together with the reason the page failed and your account identifier, for 90 days and for no more than your 50 most recent reports. It is used only to fix support for that page — never for statistics or profiling.

Apart from a page you save and a report you send, which article you were reading is something your own browser knows and our servers never learn.

When you select a sentence or phrase and ask for a translation, that text — and the word you clicked, if any — is sent to DeepSeek-V4 (Flash), run by DeepSeek (Hangzhou DeepSeek Artificial Intelligence Basic Technology Research Co., Ltd.), in mainland China. This happens only for text you explicitly select; it does not happen as you read.

We do not store the sentence or the translation on our servers. We do store a billing record that the call happened, what it cost, and when — not what it contained. DeepSeek's handling of the text is governed by their privacy policy. If you would rather no text left your browser at all, do not use the sentence-translation features; word lookup and highlighting do not involve an AI provider.

We use the following providers. Each receives only what it needs to do its job.

We do not sell personal data, and we do not share it with advertisers or data brokers. We may disclose data if we are legally required to, or to protect the service against abuse.

The operator of Catglish may view your account and billing data for customer support and accounting: your email address, plan, credit balance and credit history.

Payments are processed by Stripe. Your card number never reaches our servers — Stripe handles it and gives us back only a customer reference, your subscription status, and the last four digits for display. Refunds are covered by our Refund Policy.

Our servers and database run on Amazon Web Services (AWS) in ap-northeast-1 (Tokyo, Japan). The providers listed above operate in their own regions, so using Catglish involves your data being processed in more than one country.

• See your data. Your vocabulary list, statistics and billing history are all visible in the app.
• Delete your data. Delete your account yourself on the Settings page, or email [email protected] and we will do it for you. See “Deleting your account” below for what is removed and what is kept.
• Export your data. Ask at [email protected] and we will send you a machine-readable copy.
• Stop the extension. It only acts on pages you turn it on for. Removing it from your browser stops all local processing immediately.

Depending on where you live, you may have additional rights — including to correct your data, to object to processing, or to complain to a data protection authority. Write to [email protected] and we will honour those requests regardless of where you are.

You can delete your account at any time on the Settings page. The deletion is immediate and permanent: your sign-in account, your word list, reading statistics, lookup events, saved pages, reader documents, settings and invite code are erased, not hidden.

We keep three things, none of which names you:

• Your credit ledger and your subscription records. Financial records must be kept for accounting and tax. Once your account is gone they are tied only to a random identifier, with no name or email attached.
• Stripe's records of your payments, which Stripe keeps under its own policy.
• A keyed hash (HMAC) of your email address, and the random identifier of the account it belonged to. Signing up again with the same email does not give a second free trial or invite reward; this hash is how we tell. It cannot be turned back into your email address.

Any credits left in the account are forfeited when it is deleted. If you want a refund, ask for it under our Refund Policy before you delete the account.

Catglish is not directed at children under 14, and we do not knowingly collect their data. If you believe a child has created an account, contact [email protected] and we will remove it.

If we change what we collect or who receives it, we will update this page and the date at the top, and — for a change that materially affects you — tell you by email before it takes effect.

Privacy questions and data requests: [email protected]. Everything else: [email protected].