Grammar & Spell Checker – 5 Languages by ReadyStack

Spelling, grammar and punctuation as you type — in English, German, Spanish, Portuguese and Japanese. Free, with no account.

FREE, NO ACCOUNT
• Checks as you type in mail (Gmail, Outlook on the web), forms, posts, comments and chats
• Click an underlined word to see the fix; accept it with one click — your editor's own undo still works
• Badge with the number of issues and a list of all of them, "fix all spelling"
• Personal dictionary, ignore, turn off a rule — stored in your browser
• English (US, UK, Canada, Australia, New Zealand, South Africa), German (Germany, Austria, Switzerland), Spanish, Portuguese (Brazil, Portugal, Angola, Mozambique), Japanese
• Japanese rules other checkers miss: doubled particles (とと), です/だ style mixing, double honorifics (二重敬語), common wrong kanji (以外と→意外と), ら抜き, half-width kana, full/half-width mixing
• A full-page checker for any text (for Google Docs: copy the text in, fix it, paste it back)
• Up to 10,000 characters per field

PREMIUM — $4.99 a month or $39 a year
• AI rewrites of a sentence or paragraph: fix · clearer · shorter · formal · friendly — in all five languages, with a word-by-word preview before anything is replaced
• Picky style checks (wordiness, style, Japanese sentence length and comma use)
• Texts up to 100,000 characters per field
The free checker stays free. Get a licence key at getreadystack.com and paste it into the extension (toolbar icon → Premium).

FAST AND CAREFUL
• Reads only the field you are typing in, and sends only the lines you changed
• Nothing is added to the pages you visit
• Password, card, one-time-code and "spellcheck off" fields are never read
• Quoted e-mail and signatures are skipped

PRIVACY
The lines you change are sent over HTTPS to our own checking server (the open-source LanguageTool engine, LGPL) and forgotten after the answer; only character counts are kept for the daily limit. Premium rewrites are written by Claude Haiku 5.5 (Anthropic) or Google Gemma 4 only when you press the button. No account, no tracking, no ads.

Interface in English, Deutsch, Español, Português and 日本語. Not affiliated with LanguageTool, Grammarly or DeepL.