Grammar and Spell Checker - LanguageTool

With this extension you can check text with the free 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 word.

LanguageTool: Grammar & Spell Checker for Firefox

"Grammar and Spell Checker - LanguageTool" is a powerful Firefox add-on that checks your text for grammar, spelling, and style errors across the web. It supports over 25 languages and provides instant feedback, helping you elevate your writing with suggestions for concise phrasing, synonyms, and more. Privacy-focused, it requires no registration, ensuring your data remains secure. Ideal for both non-native and native speakers, LanguageTool enhances your writing skills effortlessly.

Add-on stats

Version: 8.14.3 (Last updated: 2025-01-14)
Creation date: 2016-06-10
Weekly download count: 9,522
Firefox on Android: No
Risk impact: High risk impact
Risk likelihood:
Manifest version: 3
Permissions:
  • activeTab
  • storage
  • contextMenus
  • alarms
Size: 13.44M

Other platforms

Not available on Chrome
Not available on Android
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Add-on summary

Check your texts for spelling and grammar problems everywhere on the web

★ Finds many errors that a simple spell checker cannot detect ★ No registration needed ★ Supports more than 25 languages (see below) ★ Works on almost any website including Gmail, Facebook, X/Twitter

This free extension ensures that your writing is error-free via the grammar and style checker LanguageTool. LanguageTool detects many errors that a simple spell checker cannot, such as grammar issues, commonly confused words, and punctuation oversights. Additionally, LanguageTool offers style suggestions to elevate your writing: synonym replacements for overused words, concise rephrasing of wordy sentences, and formal alternatives to commonly used expressions.

LanguageTool is designed with simplicity in mind, instantly analyzing your text as you type. It is compatible with most platforms, including social networks such as X/Twitter and LinkedIn, and e-mail services such as Gmail.

With LanguageTool, our aim is to give users a full-feature grammar checker and proofreader that will enable them to have control and confidence over their content. While LanguageTool is a vital extension for non-native speakers, it also recognizes many mistakes that are frequently made by native speakers. This grammar and spelling correction works across several varieties of commonly spoken languages, and is capable of distinguishing between American and British English. LanguageTool also features a personal dictionary for exceptions or words that you might commonly use, but are not found in a conventional dictionary; it will learn to recognize these words for future grammar checking and proofreading.

Unlike other services like Grammarly (a.k.a. Grammerly :-), QuillBot, and Ginger, LanguageTool supports more than 25 languages including English, Spanish, French, German, and Polish (see below for the complete list).

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User reviews

These summaries are automatically generated weekly using AI based on recent user reviews. Firefox Browser Add-ons does not verify user reviews, so some user reviews may be inaccurate, spammy, or outdated.
Pros
  • Works seamlessly across all websites unlike competitors (e.g., Grammarly)
  • Helpfulness in copywriting
  • Better than other alternatives in the free version
  • Fast and precise corrections reported by some users
Cons
  • Inconsistent corrections, suggesting incorrect tense changes
  • Issues with custom server support after specific updates
  • Breaks spell checking completely for some users
  • Difficulty in activating correction pop-ups
Most mentioned
  • Issues with tense correction and context understanding
  • Problems after updates causing loss of functionality
  • Seamless operation across different websites compared to competitors
User reviews
They can see everything you write, and they record that unencrypted data. I should never have even tried this.
by jl319, 2025-01-21

Has become very stupid. Makes incorrect "corrections" constantly, gets tense wrong, does not know words exist (it tried to correct 'withering' to 'dithering' for no reason). Used it for a while but have had to stop because it's irritating more than helping.

by Dynamax, 2025-01-20
View all user reviews

Add-on safety

Risk impact

Grammar and Spell Checker - LanguageTool requires some sensitive permissions that could impact your browser and data security. Exercise caution before installing.

Risk likelihood

Grammar and Spell Checker - LanguageTool has earned a fairly good reputation and likely can be trusted.

Upgrade to see risk analysis details