Offline Spell Check for Web Pages

Proofread any web page without sending a single byte anywhere.

Built for the people who publish pages, not the people who write essays: QA engineers, editors, technical writers and site owners who need to catch a typo before it ships.

── HOW IT IS DIFFERENT ──

100% offline. The dictionary ships inside the extension. There is no API call, no backend and no account. It cannot break because a server went away, and ad blockers have nothing to block.

No ads. Ever. No popups, no upsell interstitials.

Minimal permissions. Two permissions, and neither of them is access to your tabs or your browsing history. Installing this does not show you the "Read your data on all websites" warning, because it does not ask for that.

Does not touch the page. Some spell checkers make the whole document editable in order to borrow the browser's built-in checker — that silently kills every link on the page. This one reads the text and draws its own highlight layer in a closed shadow root. Your page is never modified.

Knows technical writing. A built-in list of programming and web terms (uri, webview, falsy, viewport, monorepo, encodings, webhooks, …) plus automatic skipping of code blocks, camelCase identifiers, acronyms, URLs, file paths and file extensions. You get your real typos instead of a red wall.

Checks the text users never see. <title>, alt text, placeholders and aria-labels are checked too — a typo there is still a typo.

Only checks English text. Elements marked with another language are skipped, so a multilingual page will not light up.

Click a highlight for suggestions, and click a suggestion to copy it.

── WHAT IT DOES NOT DO ──

Please read this before installing.

It finds misspelled words. It does NOT check grammar, and it cannot catch a mistake that is itself a real word:

"the from below" instead of "the form below" "there own files" instead of "their own files" "loose the file" instead of "lose the file"

Judging those needs to understand the sentence, not the word. Any dictionary-based checker — including Firefox's own — misses them. If you need grammar and confusable-word checking, you want an AI writing assistant instead, and it will send your text to a server to do it.

It does not rewrite, suggest phrasing, or generate text. It does not check spelling inside code blocks (on purpose). It does not check what you type into form fields, only their placeholders. It reads the page you are looking at when you click the icon, and nothing else.

── PRIVACY ──

No network requests. No analytics. No accounts. Nothing is collected, because nothing is sent. The dictionary is a local file inside the extension.

── CREDITS ──

English dictionary derived from SCOWL (Copyright 2000-2018 Kevin Atkinson and contributors), used under its permissive licence. Full licence text is bundled with the extension.