Offline Spell Check for Web Pages

Offline Spell Check for Web Pages finds misspelled words on any web page without sending a single byte anywhere. The English dictionary ships inside the extension — there is no API call, no backend, and no account.

Built for people who publish pages rather than write essays: QA engineers, editors, technical writers and site owners who need to catch a typo before it ships.

WHAT IT DOES NOT DO — please read this first. 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"). Judging those requires understanding the sentence, not the word — any dictionary-based checker, including your browser's own, misses them. If you need grammar and confusable-word checking, you want an AI writing assistant, and it will send your text to a server to do it.

WHAT IT DOES DIFFERENTLY

• 100% offline. Nothing is sent, because there is nowhere to send it.
• Minimal permissions — two of them, and neither is access to your tabs or your browsing history. Installing it does not show the "Read your data on all websites" warning.
• Never modifies the page. Highlights are drawn in a closed shadow root, instead of making the document editable to borrow the browser's built-in checker — which silently kills every link on the page.
• Knows technical writing. A built-in list of programming and web terms, plus automatic skipping of code blocks, camelCase identifiers, acronyms, URLs, file paths and file extensions.
• Checks the text users never see: <title>, alt text, placeholders and aria-labels.
• No ads. Ever.

Measured false-positive rate: 0.05% across ~65,000 words of real technical documentation, with 100% recall on non-word errors (18/18). Full method, numbers, and one optimization that was tested and rejected: https://github.com/sserpolar/offline-spell-check/blob/main/BENCHMARK.md