AI Grammar Checker

The AI Grammar Checker proofreads your writing the way a good editor would: it finds the mistakes, shows you exactly where they are, and explains why each one is wrong. Paste an essay, email, cover letter or post, and every spelling, grammar, punctuation and word-choice mistake is underlined in your own text. Click one to see the fix and the rule behind it, then accept it, ignore it, or accept everything at once.

What you get from every check

• Mistakes marked in place. Each one is underlined in your text and color-coded by type, so you never have to hunt for what changed.
• One-click fixes. Accept or ignore each suggestion, or accept all of them, then copy or download the corrected text.
• The rule behind every fix. A short explanation, written for learners, and a summary of the mistakes you make most often.
• Optional style help. Clarity and style suggestions for your goal (academic, business, casual or creative), kept separate from real mistakes.
• Your voice kept. The checker changes only what is wrong. It does not rewrite correct sentences.

How to check your grammar

1. Paste your text, or upload a .txt, .docx or .pdf file.
2. Choose your goal and, for English, the variety you write in (US, UK, Canadian or Australian).
3. Click Check grammar.
4. Click each underlined word to see the fix and its explanation, then accept or ignore it. Accept all applies every remaining fix.
5. Copy or download the corrected text, or re-check it once you have made your own changes.

Types of mistakes it finds

Choosing a goal

General suits most texts. Academic also flags contractions, slang and vague wording. Business looks for clear, concise, professional phrasing. Casual accepts relaxed language and flags only real mistakes. Creative respects deliberate choices such as dialogue and fragments.

The most common grammar mistakes

• Its vs. it's: it's means it is; its shows possession (the dog wagged its tail).
• Their, there, they're: belonging to them, a place, and they are.
• Subject-verb agreement: a singular subject takes a singular verb (the list of items is long).
• Affect vs. effect: affect is usually the verb, effect the noun.
• Then vs. than: then is about time, than compares.
• Missing comma after an introductory phrase: In my opinion, schools should…

Related tools

To add punctuation to a transcript without changing any words, use the AI Punctuation Adder. To reword a text rather than correct it, try the AI Paraphraser. If your text was written with AI and you want it to sound like you, the AI Text Humanizer rewrites it and shows before-and-after scores from our AI Content Detector.

Frequently asked questions

How do I check my grammar for free?

Paste your text or upload a file, choose your goal, and click Check grammar. Every mistake is underlined in your text. Click one to see the fix and a short explanation, then accept or ignore it, or accept them all at once. Free checks cover up to 800 words, and the examples on the page show a full result without using a check.

What kinds of mistakes does it find?

Spelling mistakes and wrong homophones (their, there, they're), grammar errors such as subject-verb agreement, verb tenses, articles and prepositions, punctuation and capitalization, and wrong or missing words. With style suggestions on, it also points out wordy, vague or awkward phrasing for your goal, listed separately from actual mistakes.

Will it rewrite my text?

No. It changes only what is wrong, as small as possible, and shows you each change before you accept it. Your voice and word choices stay yours. If you do want your text rewritten, use the AI Paraphraser.

Does it explain the corrections?

Yes. Every fix comes with the name of the rule and a one-sentence explanation, and the summary groups your mistakes by rule, so you can see which ones you make most often. That makes it useful for English learners, not just for fixing one text.

Does it support British English?

Yes. Choose US, UK, Canadian or Australian English and it follows that variety's spelling (color or colour, organize or organise) and flags spellings from the others. With Any variety, it accepts any spelling that is used consistently.

How long can my text be?

Free checks cover up to 800 words, enough for most emails and essays. With AI credits or a plan, you can check up to 2,000 words at once. You can upload .txt, .docx and .pdf files.

Can it check other languages?

Yes. It checks text in the language it is written in, and the page itself is available in 14 other languages. The explanations are written in the language of the page.