Grammar Checker

What this grammar checker does

Paste a paragraph, an email, an essay or a blog post, choose the language variety, and the checker reads it for mistakes: subject-verb disagreement, confused words, missing or doubled punctuation, spelling, capitalisation, repeated words and clumsy phrasing. Each finding comes with an explanation and, where there is an obvious correction, a button that applies it to your text.

Alongside that, the tool counts your words, sentences and characters and reports readability: average sentence length, a reading ease score, how many sentences run long, and how much possible passive voice it can see. Those figures are calculated in your browser as you type, so they work even before you run a check.

This grammar checker is free with no account, no daily cap and no suggestions hidden behind an upgrade. Each check handles up to about 20,000 characters, roughly 3,000 words, so very long documents are best done in sections.

How to use the grammar checker

1. Pick the language variety first. English (US) and English (UK) disagree about colour, organise, travelled and a long list of others. Choosing the wrong one produces a page of false alarms.
2. Paste your text. Plain text works best. If you are copying from a word processor, the formatting is dropped and only the words are checked.
3. Run the check. Results are grouped by type and colour-coded, with the problem word highlighted in its surrounding sentence so you can see the context without hunting for it.
4. Apply what is right and ignore what is not. Each suggestion has one or more replacement buttons. Clicking one edits your text immediately. The ignore button removes a flag you disagree with.
5. Use Apply all fixes carefully. It takes the first suggestion for every remaining issue at once, which is handy for a page of obvious typos and risky for style suggestions. Read the result afterwards.
6. Check the Readability tab. If the average sentence is over 25 words or a dozen sentences are flagged as long, the text will feel heavy however correct the grammar is.
7. Re-run after editing. Fixing one sentence often reveals a problem in the next.

What a grammar checker catches, and what it misses

Being clear about this saves a lot of misplaced trust.

In other words, the tool handles the mechanical layer well and the meaning layer not at all. That is still worth a lot, because mechanical errors are the ones readers notice first and the ones that quietly cost credibility in a job application, a client email or a piece of published writing.

Ten errors the checker finds most often

1. Its and it's. It's is only ever "it is" or "it has". Possessive its has no apostrophe, like his and hers.
2. Their, there, they're. Belonging, place, and "they are" respectively. Reading the sentence with the expansion substituted settles it instantly.
3. Subject-verb agreement. "The list of items is long", not "are long". The verb agrees with the subject, not with whatever noun sits nearest.
4. Comma splices. Two full sentences joined by a comma: "It was late, we went home." Use a full stop, a semicolon or a conjunction.
5. Run-on sentences. Three ideas fighting for one full stop. Splitting usually improves both grammar and readability.
6. Apostrophes in plurals. Decades and plain plurals take no apostrophe: 1990s, invoices, photos.
7. Your and you're, affect and effect, then and than. The classic real-word confusions, which a spellchecker alone will never catch.
8. Dangling modifiers. "Walking to the station, the rain started." The rain was not walking.
9. Tense drift. Starting in the past and finishing in the present within the same paragraph.
10. Doubled words and spaces. Invisible to the writer, obvious to everyone else, and the easiest thing on this list to fix.

Grammar, spelling, punctuation and style are different problems

The results are colour-coded because the four categories deserve different levels of trust.

• Grammar. Rules about how words work together. When the checker flags these it is usually right, and the fix is usually the one offered.
• Spelling. Objectively checkable, with the caveat that names, brands, technical vocabulary and non-English words will be flagged wrongly. Add them to your mental allow-list and move on.
• Punctuation. Mostly rules, partly convention. Comma placement in particular varies between British and American practice and between house styles.
• Style. Suggestions rather than corrections: wordiness, repetition, possible passive voice, unusual phrasing. Treat these as questions. Sometimes the long version is deliberate and better.

Understanding the readability numbers

The Readability tab uses the Flesch reading ease formula, which combines average sentence length and average syllables per word into a score from roughly 0 to 100. Higher means easier.

Two cautions. The formula counts syllables and sentence lengths; it has no idea whether your writing is clear. You can score 70 while being completely incoherent. And a low score is not automatically a fault, because some subjects genuinely need long words. The more useful numbers are usually the average sentence length and the count of long sentences, because those point at specific sentences you can go and shorten.

A proofreading workflow that works

Running a checker is one step, not the whole job. This order catches far more:

1. Leave it for a while. Even an hour changes what you can see. Fresh eyes notice what familiar ones skip.
2. Read it aloud. The most effective proofreading technique there is. Your mouth stumbles exactly where the sentence is broken.
3. Run the grammar check. Clear the mechanical errors so they stop distracting you from the real editing.
4. Cut ten per cent. Almost every first draft improves. Adjectives, hedges, throat-clearing openings and repeated points go first.
5. Check the structure. Does each paragraph do one job? Does the opening tell the reader what they get?
6. Read the last line first. Reading sentences in reverse order breaks the flow that makes your brain autocorrect, which is why typos survive three readings.
7. Check names, numbers and links separately. A misspelled client name undoes an otherwise perfect email, and no grammar checker will save you.

If English is not your first language

An automated checker is genuinely useful here, because the errors it is best at are the ones that most often mark writing as non-native: articles, prepositions, agreement and word order. A few habits get more out of it:

• Read the explanation, not just the fix. Applying corrections blindly produces clean text and no learning. The message usually names the rule.
• Keep a list of your repeat offenders. Most writers have four or five patterns that recur. Fixing those consciously improves your writing faster than anything else.
• Pick one variety and stay with it. Mixing US and UK spellings in one document looks careless even when every individual word is correct.
• Write shorter sentences. Long sentences multiply the chances of a grammar slip, in any language.
• Watch the articles. A, an and the are the single most common difficulty for speakers of languages that do not use them, and the checker is good at flagging them.

Checking AI-written drafts

Text produced by an AI writing tool is usually grammatically clean, which makes a grammar checker close to useless on it. The problems in those drafts are elsewhere: vague claims, repetition dressed up as structure, confident statements that are wrong, and a tone that belongs to nobody in particular.

So read AI drafts for substance rather than mechanics. Check every fact and figure against a source. Delete sentences that could appear in an article on any subject. Add the things only you have: an example from your own work, a number from your own data, an opinion you are prepared to defend. Then run the grammar check at the end, because editing always introduces new typos.

Emails, essays, applications and blog posts

What counts as a good check changes with the document.

• Work emails. Speed matters more than polish, but one habit is worth the ten seconds: check the recipient's name, the date and any figure you quoted. Those are the errors people remember.
• Job applications and cover letters. The one place to be strict. Many recruiters treat a typo as a signal about attention to detail, fair or not. Run the check, then read the letter aloud, then have someone else look at it.
• Essays and assignments. Check the mechanics here, but spend the time on structure: one idea per paragraph, a clear line of argument, evidence attached to claims. Markers reward that far more than flawless commas.
• Blog posts and web pages. Readability does real work online, where people scan rather than read. Short sentences, short paragraphs, descriptive subheadings. Check the headline and the opening paragraph twice, since those get read most.
• Social posts and bios. Short, highly visible, and often written in a hurry. Paste them in anyway; a typo in a pinned bio can sit there for years.

Privacy: what not to paste

Being straightforward about this matters more than a reassuring sentence. The grammar analysis is performed by LanguageTool's public proofreading service, which means the text you check leaves your browser and is processed on their servers. The word counts and readability figures are calculated locally and never sent anywhere.

For ordinary writing, that is fine. For anything sensitive it is not: client contracts, medical details, passwords, unpublished legal documents, personal data belonging to other people. The rule for every online checker, this one included, is simple. If you would not paste it into a public search box, do not paste it here. When you must check sensitive material, use software that runs entirely on your own machine.

Frequently asked questions

Check your writing now

Paste the thing you are about to send, run the check, fix what is genuinely wrong, then read it aloud once. That combination catches almost everything that would have embarrassed you. Back to the checker.