Grammar checker
Catch grammar, spelling, and style issues in your essays, emails, and articles. Each issue comes with a one-line explanation and click-to-apply fixes. Backed by LanguageTool, an open-source engine with strong support for English, German, French, and 25+ other languages.
How the grammar checker works
Click the Check button to send your text to the LanguageTool API, which returns a list of detected issues with suggested replacements. Each issue is tagged spelling, grammar, or style. Click any suggestion to apply it in place. The text stays in your browser until you press Check — we do not store it.
The public LanguageTool API is rate-limited to roughly 20 requests per minute per IP. For long documents, break the text into chunks of about 2,000 words. We will move to a self-hosted instance when traffic grows past the free tier.
About the Grammar checker
The grammar checker reviews a block of writing for spelling slips, grammar errors, and style wrinkles, then lists each issue with a one-click fix. It is built on LanguageTool, an open-source proofreading engine, so it catches the things spellcheck misses: subject-verb agreement, misused homophones like their and there, doubled words, and awkward phrasing.
Reach for it when you have stared at a paragraph long enough that your eye skips the mistakes. Paste an email, an essay, a cover letter, or a product description, run a check, and apply the suggestions you agree with. It handles up to 20,000 characters per check and detects the language automatically, so you can drop in text without setting anything up first.
How to use it
- Paste or type your text into the editor on the left. Up to 20,000 characters are checked in one pass.
- Press Check grammar to send the text to LanguageTool and pull back the list of issues.
- Read each issue in the right-hand panel, colour-coded as spelling, grammar, or style, with the problem word highlighted in its sentence.
- Click a suggested replacement chip to apply that fix in place; the text and remaining issues update so offsets stay correct.
- If you edit the text after a check, re-run the check before applying more fixes, since the stale-text banner warns you the suggestions no longer line up.
- Use Try sample to see how flagged issues look, or Clear to start over.
Examples
Catching a homophone and an agreement error
Input: "Their are several things which the checker will catches." The tool flags "Their" as a misspelling-style confusion and offers "There", and flags "will catches" as a verb agreement error suggesting "will catch". Two clicks fix both without touching the rest of the sentence.
Tidying a doubled word
Input: "We we should ship on Friday." LanguageTool detects the repeated "we" and offers a single "we" as the replacement, with the delete option shown as (delete). The fix collapses the duplication and the highlighted context shows exactly where the repeat sat.
A clean pass
Paste a polished sentence with no errors and the check returns zero issues with a No issues found message. That is a useful signal that the obvious mistakes are gone, though it is not a guarantee that the meaning or tone is right.
Frequently asked questions
- What engine powers the checks?
- LanguageTool, an open-source grammar and style engine. The tool sends your text to its check endpoint and maps the results into spelling, grammar, and style categories with suggested replacements for each match.
- Is there a length limit?
- Yes. A single check accepts up to 20,000 characters. For longer documents, check a section at a time. Each request also has a short timeout, so very large pastes may need splitting.
- Does it pick the right language automatically?
- It runs in auto-detect mode and reports the language it identified as a badge. If your text mixes languages, detection follows the dominant one, which can miss errors in the minority language.
- Why did a correct sentence get flagged?
- Style and grammar rules are heuristics, not absolute truth. Proper nouns, technical jargon, and deliberate fragments sometimes trip a rule. Apply only the suggestions you agree with and ignore the rest.
- Why are my fixes greyed out after editing?
- Each suggestion points to a character offset in the text you checked. If you edit afterwards those offsets shift, so the tool asks you to re-run the check first to keep replacements landing in the right spot.
Good to know
A grammar checker is a second pair of eyes, not an editor. It is strong on mechanical correctness, the kind of error that is objectively right or wrong, and weak on judgement: whether your argument lands, whether a sentence is too long, whether the tone fits the reader. Use it to clear the mechanical noise, then read the text aloud once for rhythm and meaning.
If you write in a specific dialect, note that British and American conventions differ on spelling and some punctuation, and the engine follows whichever variety it detects. For privacy-sensitive drafts, remember the text is sent to a checking service to be analysed; strip names or figures you would not want to leave your machine before running a check.