Free Grammar Checker
A rule-based checker for US English. Paste a sentence, an email, or an essay and review grammar, spelling, and punctuation suggestions as you type.
Checks US English spelling and common writing patterns in your browser.
Saved words stay in this browser until you remove them or clear site data.
Free from the team behind Typeahead. The autocomplete for your whole Mac.
Get TypeaheadWhat is a grammar checker?
A grammar checker reviews writing for patterns that may be incorrect, incomplete, or hard to follow. This one is rule-based, not AI, and it checks US English. It looks for subject-verb agreement slips, commonly confused words, repeated words, missing capitals, fragments, comma splices, overlong sentences, misspellings, and common punctuation errors. Each underline comes with the rule behind it, and nothing changes until you accept it.
Why It Matters
Small errors can interrupt a clear idea.
Grammar helps readers understand how words and clauses fit together. This checker marks selected sentence-level patterns, explains what may be wrong, and lets you decide whether each change fits your meaning.
Source: Purdue OWL, Grammar
Where it matters
Emails, essays, reports, applications, project updates, articles, proposals, and any draft where a small error could distract the reader.
Runs a fixed set of US English grammar, spelling, punctuation, capitalization, structure, and clarity rules in your browser as you type. It is rule-based, and every correction is optional.
How It Works
Check the draft as it changes.
Add your text
Paste a draft or keep writing directly in the editor.
Review the underlines
Open each marked passage to see its category and explanation.
Choose every change
Apply a clear correction, dismiss it, or revise the passage yourself.
See It Work
Seven fixes in three sentences.
What you paste
Their is a problem with the the report. Its going to be late, and your right that the numbers is wrong. I could of finished it, the deadline moved.
There is a problem with the report. It's going to be late, and you're right that the numbers are wrong. I could have finished it; the deadline moved.
This is the checker's actual result for that text: three confused words, a repeated word, a verb that did not match its subject, “could of”, and a comma splice.
How do I check my sentence?
Paste the sentence into the editor. There is no button to press, and the check finishes almost as soon as the text appears. Anything the rules object to gets a red wavy underline. Click it to see the category, a one-line reason, and a suggested replacement where a safe one exists. A fragment or an overlong sentence has no automatic fix, so you get a hint on how to repair it yourself. If nothing is underlined, none of the rules fired, which is not the same as a guarantee that the sentence is perfect.
What It Checks
Six groups of rules, all explainable.
Every rule is written down and narrow, so the checker prefers staying quiet to guessing. This is the full list of what it looks for.
Grammar
Selected subject-verb agreement and article errors, repeated words, missing sentence capitals, and phrases like “could of”.
Confused words
Their and there, its and it's, your and you're, then and than, to and too, affect and effect, lose and loose.
Spelling
Words a US English dictionary does not recognize, with nearby spellings to choose from or your own replacement.
Punctuation
Sentence endings, spacing, repeated marks, list colons, clause commas, and unmatched brackets.
Sentence structure
Likely fragments, such as a lone “Because it was late.”, and two full sentences joined only by a comma.
Clarity
Long sentences carrying several ideas, with a hint on where to split them.
Is it a good grammar checker for emails?
Email is where this kind of checker earns its place, because email errors are fast-typing errors. A doubled word, its where you meant it's, your for you're, a sentence that never got its period, two thoughts spliced with a comma: all of these are rules here. Greeting and sign-off lines such as “Hi Sarah,” and “Best,” are left alone. It will not tell you whether the message is too blunt or too long. Since the check runs in your browser, a confidential email stays on your machine.
Before the Grammar Check
Keep the first draft moving.
A grammar check happens after you write. Typeahead works during: it is a Mac app that suggests the rest of your sentence inline, in Mail, Slack, Word, and every other app. Press Tab to accept one, or keep typing to ignore it.
Private in the same way this checker is. The model runs on your Mac and your writing is never sent to a server. $79 once, no subscription.
Get TypeaheadGrammar Checker
Common questions.
A grammar checker reviews writing for patterns that may be incorrect or unclear. This one is rule-based and checks US English: a fixed set of grammar, spelling, punctuation, capitalization, sentence-structure, and clarity rules, each with a written explanation. It never rewrites your draft on its own.
Yes. Paste a single sentence and it is checked the moment it lands. For one sentence the useful rules are subject-verb agreement, commonly confused words, repeated words, a missing capital or final period, and whether the sentence is a fragment or two sentences joined by a comma.
Yes. Paste the email before you send it. It catches what slips through when you type fast: a doubled word, its for it's, your for you're, 'could of', a sentence with no period. It does not assess tone, and the email is never uploaded.
Repeated words, selected subject-verb agreement and article errors, commonly confused words (their and there, its and it's, your and you're, then and than, to and too, affect and effect, lose and loose), phrases like 'could of', sentence capitalization, likely fragments, comma splices, long sentences, US English spelling, and common punctuation patterns.
Rule-based. Every underline comes from a specific written rule or from a US English spelling dictionary, so the same text always gets the same result and each suggestion can explain itself. The trade-off is reach: it will miss errors that need an understanding of meaning, which an AI checker might catch.
Yes. Proofreading is the last pass on a near-final draft, after the ideas and structure are settled. Paste the whole piece, work down the suggestions, then read it once more yourself. Names, specialist terms, and deliberate style choices will need your judgment.
It checks an essay's mechanics: spelling, grammar, punctuation, and sentence structure. It does not grade your argument, verify facts, look for plagiarism, or check citations. Use it where your school or instructor allows writing tools, and stay responsible for the final wording.
Not yet. Spelling is checked against a US English dictionary, so 'colour' and 'organise' will be underlined. Dismiss those, or save the word so it is not flagged again in this browser.
No. Meaning, dialect, specialist terms, names, quotations, and intentional style depend on context. The checker favors conservative, explainable suggestions, so a careful final read still matters.
It is free with no account, sign-up, or card. Your text goes nowhere: the rules and the dictionary are downloaded to your browser and the check runs there, so your draft is never sent to us.
Finish the thought before the final check.
Typeahead suggests the rest of each sentence as you type, on-device, in every Mac app. Check the grammar here when you are done.
Get Typeahead — $79Mac only. One-time purchase. Runs offline.