Best Free Grammar Checkers Compared - Grammarly vs LanguageTool vs ToolBox

# Best Free Grammar Checkers Compared - Grammarly vs LanguageTool vs ToolBox

You typed something. You want to make sure it doesn't have embarrassing typos or grammar mistakes. So you search "free grammar checker" and get hit with a wall of options, most of which want your email address before they'll check a single sentence.

Here's a breakdown of the three most relevant free grammar checking options in 2026, what they actually do with your text, and which trade-offs you're making with each one.

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The Three Contenders

Grammarly is the biggest name in this space. It's what most people think of when they hear "grammar checker." It has a browser extension, a desktop app, and a web editor.

LanguageTool is the open-source engine that powers a lot of grammar checking tools. It has its own website and browser extension, plus an API that other tools can use.

ToolBox (Grammar & Spell Checker) uses the LanguageTool API under the hood but wraps it in a simpler interface with no account requirements.

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Feature Comparison

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Privacy - What Happens to Your Text

This is where things get interesting, and where most people don't bother to look.

Grammarly

Grammarly requires you to create an account before you can check anything. That means every piece of text you check is tied to your identity. Their privacy policy states they collect "user content" including "text, documents, or other content or information provided by you." They also collect usage data, device information, and use third-party analytics.

If you use the browser extension, Grammarly can read text on every page you visit. The extension requests permission to "read and change all your data on all websites." That's a significant amount of access for a grammar checker.

Grammarly uses your content to improve their models and services. They say they don't sell your data, but they do share it with "service providers" and "business partners."

LanguageTool

LanguageTool is more privacy-conscious than Grammarly. The open-source version can be self-hosted, which means zero data leaves your machine. The hosted version (languagetool.org) sends your text to their servers for analysis.

Their privacy policy is shorter and more straightforward. They log anonymized snippets of checked text for quality improvement but state they don't tie it to user accounts. However, their website does prompt you to create an account, and the free tier nags you to upgrade.

ToolBox

ToolBox sends your text to the LanguageTool API for checking - the same engine, same analysis. The difference is that ToolBox doesn't have user accounts. There's no login, no signup, no email collection. Your text goes to LanguageTool's API, gets analyzed, and the results come back. ToolBox doesn't store your text on any server.

Error results are displayed with color-coded underlines - red for spelling errors, blue for grammar issues, yellow for style suggestions. You also get a readability score and overall quality score, which neither Grammarly (free) nor LanguageTool's website surface without additional steps.

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Accuracy - Do They Catch the Same Errors?

Since ToolBox and LanguageTool use the same engine, they catch the same errors. That's not a surprise - they're literally running the same checks.

Grammarly uses its own proprietary engine, which is generally strong on English grammar but doesn't support other languages on the free tier. LanguageTool (and by extension ToolBox) supports English, German, French, Spanish, Portuguese, Dutch, Italian, Russian, Polish, and more.

For English text, both engines catch most common errors: subject-verb agreement, misused homophones (their/there/they're), comma splices, and run-on sentences. Grammarly tends to catch more nuanced style issues, but locks most of those behind the Pro plan ($12/month).

LanguageTool's style suggestions are available for free across all platforms that use its API, including ToolBox.

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The Upsell Problem

Grammarly's free tier exists to funnel you toward Grammarly Pro. You'll see "Premium suggestion" badges on errors it won't fix unless you pay. The free version works, but the constant upselling is distracting.

LanguageTool does this too, though less aggressively. Their website shows a banner for the premium plan and locks some advanced checks behind it.

ToolBox doesn't upsell grammar features. The LanguageTool integration works the same for every visitor.

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When to Use Which

Use Grammarly if you want a browser extension that checks your writing everywhere - Gmail, Google Docs, social media. The extension is genuinely useful if you don't mind the privacy trade-off of giving Grammarly access to everything you type.

Use LanguageTool if you need multi-language support and want the option to self-host the engine. It's also the better choice if you're building something that needs a grammar API.

Use ToolBox if you want to paste in some text, get it checked, and move on. No account. No extension to install. No upsell interruptions. Open the page, paste your text, click check, fix errors, done.

The grammar checking engine is the same across LanguageTool and ToolBox. The difference is the wrapper. ToolBox gives you the cleanest path from "I have text" to "my text is fixed."

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Try It

ToolBox Grammar & Spell Checker - free, no signup, instant grammar and spell checking with readability scores.