Grammar Firefox add-ons

Grammar and spell checkers, proofreading and punctuation tools. 311 live add-ons carry the topic.

Tags come from each listing's name, category and description, read in English: a listing written in another language is tagged only where it uses the English words.

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  1. Euskalbar↗

    by Juanan Pereira Varela · updated 2025-10-22

    Basque dictionaries and other tools (corpora, spellcheckers, search engines...). Euskalbar is a Firefox toolbar that helps translating words from Basque to other languages and from other languages to

    Language Support v5.2
    Daily users 1,393 +107 wk
    Rating 4.2 13 ratings
    Growth · week +8.7% weekly avg over 11 days

  2. Private Grammar Checker - Harper↗

    by Elijah Potter · updated 2026-10-16

    A private grammar checker for 21st Century English

    Language Support v2.13.0
    Daily users 6,047 +204 wk
    Rating 4.1 68 ratings
    Growth · week +3.6% weekly avg over 11 days

  3. Definer: Word Translator, Ask AI, Popup Dictionary↗

    by Lumetrium · updated 2026-10-22

    Use AI translator and dictionary online with AI search to spell check sentences & learn new words

    Search Tools v2.1.2
    Daily users 4,005 +84 wk
    Rating 4.6 148 ratings
    Growth · week +2.2% weekly avg over 11 days

  4. Grammarly: AI Writing and Grammar Checker App↗

    by Grammarly · updated 2026-04-24

    From blank page to polished draft, Grammarly’s AI helps you write faster and stronger. Get real-time grammar fixes, tone transformations, and instant content generation right where you write in Firefo

    Language Support v8.937.0
    Daily users 541,165 +10,778 wk
    Rating 4.1 3,226 ratings
    Growth · week +2.1% weekly avg over 11 days

  5. Antidote Connector for Firefox↗

    by Druide informatique inc. · updated 2026-10-09

    Integrate Antidote with Firefox to proofread your writing in real time, to check your spelling and grammar, and to consult the dictionaries and language guides, all without ever leaving the browser!

    Language Support v12.4.5
    Daily users 21,178 +390 wk
    Rating 4.7 138 ratings
    Growth · week +1.9% weekly avg over 11 days

  6. Wordtune: AI Writing, Paraphrasing & Grammar Tool↗

    by AI21 · updated 2025-04-09

    With Wordtune, your AI writing companion, you can easily paraphrase, rewrite, correct grammar and more — all for free. In just a few clicks, you can turn your scattered thoughts into exactly what you

    Language Support v9.16.1
    Daily users 1,374 +25 wk
    Rating 3.4 14 ratings
    Growth · week +1.9% weekly avg over 11 days

  7. Grammar and Spell Checker - LanguageTool↗

    by LanguageTooler GmbH · updated 2026-08-20

    With this extension you can check text with the style and grammar checker LanguageTool. It finds many errors that a simple spell checker cannot detect, like mixing up there/their, a/an, or repeating a

    Language Support v11.3.1
    Daily users 330,102 +3,765 wk
    Rating 4.3 5,406 ratings
    Growth · week +1.2% weekly avg over 11 days

  8. ProWritingAid↗

    by ProWritingAid · updated 2026-10-22

    Gain confidence in your writing with the best grammar checker and paraphrasing tool that works wherever you do.

    Language Support v2.9.43974
    Daily users 2,411 +18 wk
    Rating 3.1 28 ratings
    Growth · week +0.8% weekly avg over 11 days

  9. Grammalecte [fr]↗

    by Algoo · updated 2025-12-22

    French grammar checker. Included: conjugation tool, lexicographer, text formatter and spelling dictionaries.

    Language Support v2.3.0
    Daily users 11,659 -701 wk
    Rating 4.3 103 ratings
    Growth · week -5.5% weekly avg over 11 days