Which kind of checker you need
The checkers in this list work in four different ways. Pick by where you write, not by the longest feature list:
| Kind | Examples | Good for |
|---|---|---|
| Browser extension and apps | LanguageTool, Grammarly, Microsoft Editor, ProWritingAid | Checking text in email, web forms and online editors as you type |
| Built into your editor | Google Docs, Word for the web | Documents you already write there, no extra install |
| Runs on your device | Harper, Vale, a local LanguageTool server | Private or confidential text, offline work, code editors |
| Readability and style | Hemingway Editor, Vale | Shorter sentences and a consistent house style rather than spelling |
If you write in more than one language, check the language list first. Harper currently only supports English, Google Docs offers spelling and grammar suggestions in six languages, Microsoft Editor names more than 20 languages and LanguageTool more than 30 languages and dialects.
Free limits compared
The numbers below are from the official pricing pages, help articles and repositories on the date in the table. An empty cell means the page states nothing for the free version.
| Checker | How much is free | What the free version leaves out |
|---|---|---|
| LanguageTool | 2,000 characters per text field | Premium shows all errors; 3 AI sentence rephrasings a day |
| Grammarly | Spelling and grammar, 100 AI prompts a month | Sentence rewrites, tone adjustment, plagiarism and AI text detection |
| ProWritingAid | 500 words at a time, 10 rephrases a day | Unlimited reports and rephrases, custom style guides |
| Scribens | 8,000 characters a day | Extensions, higher capacity, ad-free use |
| Microsoft Editor | Basic spelling and grammar with a free Microsoft account | Clarity, conciseness, formality and vocabulary refinements |
| Hemingway Editor | Readability score and highlights | Grammar fixes and AI rewrites (Plus) |
| Google Docs | Spelling and grammar in Docs | |
| Harper, Vale | No cap, open source on your device |
Hemingway Editor Plus costs $10 a month or $100 a year, and the offline Hemingway Editor Classic for Mac and Windows is a $19.99 purchase. Grammarly's plans page lists a Free plan at no cost and states no cap on suggestions for it.
Privacy: what leaves your device
Most grammar checkers send your text to a server to check it. What the privacy pages and docs say about that text:
- Harper: "Every check happens locally", with no telemetry and no LLM in the loop.
- Vale runs on macOS, Windows and Linux entirely offline, with no account and no upload.
- LanguageTool's privacy policy says inputs from LanguageTool users are not used to train its language models. The FAQ says texts checked with the browser add-on are usually not saved, while texts in the editor are saved to your account.
- Grammarly is now part of Superhuman, whose privacy policy says it receives the text you enable it to access, lets you decide whether your content is used to train its AI models, and does not sell user content.
- ProWritingAid's privacy policy says submitted texts and their improvements are deleted once the check is done, and documents you save in the web editor are stored encrypted in the cloud.
- Hemingway Editor's privacy policy says your document normally stays in your browser; AI features send text to Hemingway and its AI providers, which do not use it to train models.
- Scribens states on its home page that no text is saved on its servers or shared with third parties.
- Microsoft Editor in Word needs an internet connection and Intelligent Services switched on, so the check runs on Microsoft's service.
For contracts, health records or anything under a confidentiality agreement, an on-device checker or a LanguageTool server on your own computer keeps the text where it is.
Open source and self-hosted checkers
Three projects in this list publish their code under a named license:
- LanguageTool: the core is LGPL 2.1 or later. The server guide runs it with Java 8 or later on your own computer, where it is local-only by default, and the browser add-on can be pointed at that local server under Experimental settings.
- Harper (Apache-2.0) runs as a macOS app, a Chrome, Edge and Firefox extension, and plugins for VS Code, Obsidian, Neovim, Zed and WordPress.
- Vale (MIT) is a prose linter: it brings no opinions of its own and checks your text against styles you choose, such as published guides from Microsoft, Google or Red Hat, or your own terms list.
Vale fits teams with a style guide; Harper and LanguageTool cover everyday grammar.
What our tools add
A grammar checker catches mistakes; it does not tell you whether a text is easy to read or the right length. Our tools run in your browser:
- The readability checker gives Flesch Reading Ease and grade levels and highlights long sentences, and the word counter shows words, characters and reading time for a limit like ProWritingAid's 500 words.
- The AI phrase finder marks words that make a text sound machine-written, and the AI text cleaner removes markdown, hidden characters and odd spaces from text copied out of a chatbot.
- The case converter fixes headings in Title Case or Sentence case.
For the writing itself, our plain language rules cover short sentences and plain words, and the em dash, en dash and hyphen guide explains a punctuation question most checkers leave alone.
Frequently asked questions
Which free grammar checker works in the most languages?
Scribens states that it corrects texts in more than 40 languages and LanguageTool names more than 30 languages and dialects. Microsoft Editor supports more than 20 languages, and Google Docs offers spelling and grammar suggestions in English, Spanish, French, German, Portuguese and Italian. Harper currently supports English only.
Which grammar checkers run on my own computer?
Harper checks everything locally and says your data never leaves your device. Vale runs entirely offline on macOS, Windows and Linux. LanguageTool can run as a local server with Java 8 or later, and its browser add-on can use that server. Hemingway Editor Classic also works without internet, but it is a paid desktop app.
How much text can I check for free?
LanguageTool's free version checks up to 2,000 characters per text field, ProWritingAid gives suggestions for 500 words at a time, and Scribens allows 8,000 characters a day. Grammarly's plans page states no cap on suggestions for the Free plan but limits AI prompts to 100 a month. Harper and Vale have no cap because they run on your device.
Does the free version of Grammarly check grammar?
Yes. Grammarly's Free plan includes spelling and grammar corrections and shows your writing tone. Rewriting full sentences, adjusting tone, plagiarism detection and AI text detection are marked unavailable on the Free plan.
Do grammar checkers use my text to train AI?
It depends on the service. LanguageTool says inputs from its users are not used to train its models, Hemingway says it and its AI providers do not train on your content, and ProWritingAid says your texts are not used to improve its services. Grammarly's owner Superhuman lets you decide in your account whether your content is used to train its AI models. Harper and Vale do not send your text anywhere.
Is Hemingway Editor a grammar checker?
The free version scores the readability of your writing and flags wordy sentences, passive voice and words with simpler alternatives. Grammar fixes and AI rewrites are part of Hemingway Editor Plus, which costs $10 a month or $100 a year.