Does any of this upload my document?

No. The grammar dictionary is downloaded from the site once and then runs inside a background worker in your own tab, and the style, word and readability checks are plain rules that need no download at all. No request carries a word of your draft. An end-to-end test types a messy sample into every writing tool and fails the build if a single off-origin request appears.

How big is the grammar dictionary, and when does it download?

About 15.1 MB. It starts downloading when the grammar page opens, before you type, and the strip above the editor shows its size and an Engine ready marker when it has compiled. If it cannot load, the page says so and keeps the style checks running rather than showing a spinner forever.

Does it work offline?

Once the page and the dictionary are loaded, checking needs no network at all, so a plane or a locked-down network is fine for the rest of the session. The strip also has a Save for offline button. Unlike the OCR and video engines, though, the grammar binary is not pinned by the site's offline cache, so test a cold offline start on your own machine before you rely on it.

It keeps flagging a name I use. Can I teach it?

Yes. Spelling cards carry an Add to my dictionary button. The word is stored in this browser only, lowercased and matched with punctuation trimmed, up to 2000 entries. There is no sync, no backup and no list to edit in the app, so clearing site data for GoChronos also clears your dictionary.

Which English does it check?

The English row offers American, British, Canadian, Australian and Indian. One caveat in the current build: the engine is created once, when the page loads, with American selected, and switching the row afterwards does not rebuild it. Treat the picker as a preference rather than a guarantee and check non-American spellings by eye.

How to Proofread a Document Without Uploading It

Proofread a whole draft in your browser: spelling and grammar from an on-device dictionary, then cliches and filler, then the sentences that read hard.