AI Grammar Checker
Correct the document while preserving its voice, paragraph order and meaning. Try the same tool available in your dashboard, then carry your input, options and result into your account.
Correct the document while preserving its voice, paragraph order and meaning.
Add at least 3 words to document.
The complete document comes back with grammar, spelling and punctuation fixed in place.
What a free AI grammar checker corrects, and what it leaves alone.
The second half of that sentence matters as much as the first. A checker that changes everything it could have phrased differently is unusable on writing with a voice.
- GrammarAgreement between subject and verb, tense that stays put across a paragraph, pronouns that point at something, and the comparatives that go wrong under editing. Most real grammar errors in adult writing are not ignorance; they are the residue of a sentence that got rewritten halfway through, leaving a verb agreeing with a noun that is no longer there.
- Spelling and typosIncluding the ones a spellchecker cannot see, because the word is spelled correctly and is simply the wrong word. Their and there, its and it's, complement and compliment, and the transposition that turns one real word into another. Context is what catches these, which is why the check reads the sentence rather than the word.
- PunctuationComma splices, missing serial commas where the sentence is genuinely ambiguous without one, apostrophes on plurals, and quotation marks that never close. Punctuation errors change meaning more often than people expect, and they are the errors a reader notices fastest.
- Clarity, where it is genuinely unclearA sentence that can be read two ways gets flagged. A sentence you simply wrote in a way we would not have does not, because that is your voice and it is not an error. The distinction matters: a checker that rewrites everything it could have phrased differently is unusable on anything with a style of its own.
- What is deliberately left aloneYour register, your vocabulary, your sentence length, and any deliberate fragment. Also every fact, figure, name and quotation, which come back exactly as written. A grammar check is not a rewrite, and the moment it starts changing what you meant it has stopped being useful.
Why a grammar check on AI text comes back clean and the draft is not.
Run a conventional grammar checker over something ChatGPT or Claude wrote and it will find almost nothing. That is not a compliment to the draft and it is not a failure of the checker. A language model is trained on enormous quantities of edited prose, so producing grammatical sentences is the one part of writing it never struggles with. Everything that is actually wrong with the draft sits somewhere a grammar check does not look.
- The grammar is already right, and the writing is still wrongThis is the thing that surprises people. Model output almost never contains a conventional grammar error, so running a standard checker over it returns nothing and you conclude the draft is finished. It is not. What is wrong with it is rhythm, repetition and structure, none of which a grammar check is looking at.
- Confident sentences about things that are not trueGrammatically immaculate and factually invented. No checker on the internet catches this, ours included, and any tool implying otherwise is overselling. If a draft came from an assistant, the names, dates, figures and citations need checking by a person, and that person has to be you.
- Markdown and formatting that survived the pasteAsterisks that were meant to be bold, hash marks that were meant to be headings, numbered lists sitting inside what should have been a paragraph. These are not grammar errors, so a grammar checker walks past them, and they are the most visible sign of where a document came from.
- Hedging that outlived its sourceText from a research assistant is built around citations. Remove the brackets before pasting and the hedging stays behind, so you get sentences leaning on evidence that is no longer anywhere in the document. Grammatical, and structurally incomplete.
Checking grammar in ChatGPT, Claude, Gemini, Grok, DeepSeek and Perplexity text.
Each one leaves a different residue, and only some of it is the kind of thing a grammar check was built to find.
ChatGPT grammar checker
The cleanest grammar of any assistant, which makes a conventional check almost useless on it.
Run a grammar checker over ChatGPT output and it returns nothing, because a model trained on enormous quantities of edited prose does not produce agreement errors or comma splices. That silence is easy to read as a finished draft and it is not one.
What it does produce is the three-part shape, the stock transitions and the vocabulary everybody now recognises. None of that is ungrammatical, so none of it is flagged. If a ChatGPT draft comes back clean and still reads as machine-made, the check did its job and the job was the wrong one.
Gemini grammar checker
The one where a grammar check finds real errors, for a structural reason.
Gemini returns bullets and headings by default, and text converted from a list into prose is where genuine grammar problems appear: fragments that were fine as list items, verbs that no longer agree once two bullets are joined, and articles missing from what used to be a heading.
So on Gemini output the check is worth running twice. Once on the draft as it arrives, and again after you have turned the lists into paragraphs, because that conversion is what introduces the errors.
Grok grammar checker
Conversational writing breaks more rules on purpose, and a checker cannot tell which.
Grok writes with sentence fragments, comma splices used for pace, and one-line paragraphs — deliberate choices in an informal register and flagged as errors by any checker reading rules rather than intent. Accepting every suggestion flattens exactly what made the draft readable.
The corrections worth taking are the ones that are wrong in any register: agreement, tense that slips mid-sentence, the wrong homophone. Leave the fragments if the piece is meant to sound like somebody talking.
Claude grammar checker
Claude produces the cleanest prose of the major assistants, which changes what a check is for rather than removing the need for one.
Conventional errors are close to absent. What arrives instead is heavy Markdown, because Claude structures aggressively: bolded lead-ins, bulleted breakdowns, headed sections in text that was supposed to be a paragraph. Pasted into a document, that formatting either renders as literal asterisks or silently reshapes the page.
The second habit is qualification. Claude hedges more than the others, so sentences accumulate subordinate clauses narrowing a claim that was fine as stated. Those are not grammar errors and they are worth cutting, which is a judgement call the check surfaces rather than makes for you.
DeepSeek grammar checker
DeepSeek needs a check more than the others do, and for a reason that has nothing to do with grammar.
Text pasted from a reasoning response frequently still carries the reasoning: a preamble that plans the answer, or an opening paragraph that talks about what it is about to say. That is the first thing to remove and no grammar checker will flag it, because there is nothing ungrammatical about it.
Its English is also occasionally stiff in a way the hosted Western assistants are not, with article use and preposition choice being the two places it slips. Those are real errors and they are exactly what the check is for.
LLaMA grammar checker
LLaMA is weights rather than a product, so what you need to fix depends on which application served it to you.
Smaller quantised deployments produce genuine grammar errors at a rate the hosted assistants do not: dropped articles, tense that wanders inside a paragraph, agreement failures in long sentences. Larger deployments behind a good system prompt produce almost none. The same model name covers both.
That variability is the practical point. With LLaMA output it is worth actually reading the corrections rather than accepting them, because the error rate is unpredictable in a way it is not with ChatGPT or Claude.
Perplexity grammar checker
Perplexity writes to be cited, and the citations are usually gone by the time the text reaches a document.
What that leaves is sentences built around a bracket that is no longer there. Clauses attributing a claim to a source, qualifiers positioning one finding against another, and constructions that only made sense with a reference attached. Each is grammatical and several are now incomplete in meaning.
The check catches the ones that became actually ungrammatical when the marker was deleted, which is more common than you would think, since people tend to remove the bracket and leave the surrounding punctuation.
A free Grammarly alternative, and when it is not the right one.
People searching for a free Grammarly alternative usually want one of two quite different things, and the distinction decides whether this page is any use to you.
If you want continuous correction everywhere you type, an extension is the right shape of tool and this is not it. Grammarly and LanguageTool both install into the browser and follow you into every text field. That is genuinely convenient and it is a different product from a page you paste into. We are not going to pretend otherwise to win the comparison.
If you want to check a document you have already written, this does that job free, with no account and no install, for up to 3,000 words a check and 3 checks a day. That covers most of what people actually use a grammar checker for: an essay before submitting it, an application before sending it, a report before it circulates.
The other honest difference is what happens to your text. An always-on extension reads everything you type in every field, which is a large amount of trust to extend for a comma. Pasting a document into a page scopes that to the document you chose.
AI grammar checker questions.
Is this AI grammar checker free, and is a sign-up needed?
It is free to use on this page and you do not need an account to start. Signing in gets you your documents saved between visits, which matters for anything longer than a paragraph and not at all for a quick check.
What does an AI grammar checker fix?
Grammar, spelling, punctuation and genuine ambiguity. Subject-verb agreement, tense consistency, comma splices, apostrophes, and the wrong-word errors a spellchecker cannot see because the word is spelled correctly. It leaves your register, vocabulary and sentence length alone, along with every fact, figure and quotation.
Is this a free Grammarly alternative?
For checking a document, yes, and it is worth being clear about the difference. Grammarly is an always-on layer that follows you into every text field via a browser extension and desktop app. This is a page you paste into. If what you want is continuous correction as you type everywhere, an extension is the right shape of tool. If what you want is to check a document you have already written, without installing anything, this does that job free.
Can it check grammar in ChatGPT, Claude, Gemini and DeepSeek text?
Yes, and it is worth knowing what you will and will not get. Model output rarely contains conventional grammar errors, so the check often comes back nearly clean on a draft that still reads as machine-made. What is wrong with those drafts is rhythm, repetition and structure, which is a different job from grammar.
Will it change my writing style?
No, and that is deliberate. It corrects errors and flags sentences that are genuinely ambiguous. It does not rewrite phrasing it merely would have chosen differently, because doing that to anything with a voice of its own makes the tool useless on exactly the writing that is worth keeping.
Does it catch things that are wrong rather than ungrammatical?
No, and no tool does. A sentence can be perfectly constructed and completely false, which is the specific failure mode of AI-drafted text. Names, dates, figures and citations in anything a model wrote need checking by a person.
Does it work for non-native English speakers?
That is a large part of what it is for, and it is worth saying that writing English as a second language is not a defect to be corrected. The check fixes errors: articles, prepositions, tense. It does not flatten your writing into a single register, and it will not penalise you the way an AI detector does, which is a real and separate problem worth knowing about.
Is it good enough for academic work?
For grammar, spelling and punctuation, yes. It does not check citation formatting against a style guide, it does not verify sources, and it cannot tell you whether an argument holds. Your institution's academic-integrity policy applies to the finished work regardless of what any tool corrected in it.
Does fixing grammar lower an AI detection score?
Usually not, and it can raise one. Detectors measure how predictable a passage is, and correcting errors makes text more regular rather than less. If that is what you are actually trying to do, a grammar check is the wrong tool for it.
Is my text stored?
The document is attached to your account so you can come back to it, and you can delete it whenever you like. It is not used to train anything.