Yes, AI grammar checkers reliably catch most spelling, punctuation and grammar slips, but none catches everything and some add mistakes, so read the final version yourself. For most people we recommend Grammarly, because it checks as you type in more than a million sites and apps and its free plan covers spelling and grammar; Pro is $12 a month billed yearly. If you write in more than one language or want the strongest free checker in an independent test, use LanguageTool.
Grammar checkers are mature, everyday tools with free plans, though an independent test still found wide gaps in how many errors each one fixed.- Our pickGrammarlyFree; Pro $144/year ($12/month) or $30 monthly
- Best free optionLanguageToolFree; Premium €59.89/year or €19.90/month
- Best for long reports and essaysProWritingAidFree; Premium $120/year, $30/month or $399 lifetime
- Best for clear, simple writingHemingway EditorFree web version; Plus from $100/year; desktop app $19.99
Grammarly: our pick
Best for most people who want mistakes caught as they type, in email, docs and the browser.
Grammarly's biggest advantage is reach. It gives real time feedback across more than a million websites and apps, with desktop apps for Windows and Mac, browser extensions for Chrome, Safari, Firefox and Edge, a Microsoft Office add in, a Google Docs integration and phone apps How Grammarly works ↗. That means it checks your Gmail draft, your Word report and your LinkedIn message without copying text into a separate editor.
The free plan covers grammar and spelling corrections, shows your tone, and includes 100 AI prompts a month Grammarly plans ↗. Pro adds full sentence rewrites, tone adjustment, fluent English suggestions, plagiarism and AI text detection, and 2,000 AI prompts per member a month, with a 7 day free trial Grammarly plans ↗. Pro costs $144 a year, which averages $12 a month, or $30 billed monthly Grammarly Pro cost ↗.
Free Grammarly is not the most thorough checker. In a Scribbr test with 20 planted errors, free Grammarly fixed 11, and Scribbr estimated Premium would have caught about 15 Scribbr grammar checker test ↗. On privacy, Grammarly says it does not sell your content and does not let its AI model providers train on user content, but it may use de identified samples to improve its own service unless you opt out Grammarly privacy ↗.
Why we like Grammarly
- Checks as you type in more than a million sites and apps
- Free plan covers spelling and grammar
- Pro adds rewrites, tone changes and plagiarism checks
- 7 day free trial of Pro
- Says it does not sell your content
Where Grammarly falls short
- Free plan fixed only 11 of 20 errors in Scribbr's test
- Pro is $30 on monthly billing
- You must opt out to keep samples out of training
LanguageTool: best free option
Best for writers who need a strong free checker or work in more than one language.
LanguageTool checks more than 30 languages, with its deepest premium checks in English, German, French, Spanish, Dutch, Polish and Portuguese LanguageTool Premium ↗. In the same Scribbr test, it fixed 19 of 20 planted errors, the best result among tools not owned by Scribbr's parent company Scribbr grammar checker test ↗. It works in Chrome, Edge, Firefox and Opera, in Gmail, Outlook (in beta), Apple Mail and Thunderbird, and in Google Docs, Word, Apple Pages and LibreOffice, with apps for macOS, Windows and iOS LanguageTool Premium ↗.
The free plan checks up to 2,000 characters per text field and allows 3 AI sentence rephrasings a day LanguageTool Premium ↗. That is fine for emails but short for a report, roughly a few paragraphs at a time. Premium raises the limit to 150,000 characters, makes rephrasing unlimited and adds more than 20,000 extra grammar, punctuation and style checks plus a personal style guide LanguageTool Premium ↗.
Prices did not display on LanguageTool's premium page when we checked, but its help center lists Premium at €19.90 a month, €59.89 a year (about €4.99 a month) or €99.90 for two years LanguageTool prices ↗ LanguageTool Premium ↗. There is a 14 day money back guarantee LanguageTool Premium ↗. LanguageTool says texts written through its browser add on are usually not saved, while texts in its own editor are saved and synced LanguageTool Premium ↗.
Why we like LanguageTool
- Fixed 19 of 20 errors in Scribbr's test
- More than 30 languages
- Works in browsers, email apps, Docs, Word and Pages
- Low yearly price
- 14 day money back guarantee
Where LanguageTool falls short
- Free plan limited to 2,000 characters per field
- Prices shown in euros; US prices did not display on its page
- Only 3 AI rephrasings a day on free
ProWritingAid: best for long reports and essays
Best for students and professionals who want detailed style reports on long documents.
ProWritingAid is built for editing long pieces. Premium includes more than 25 writing analysis reports, a custom style guide, unlimited line editing reports and unlimited rephrasing ProWritingAid pricing ↗. It works in Google Docs, Microsoft Word and its own desktop editor ProWritingAid pricing ↗. If your problem is not typos but repetitive sentences, weak verbs or uneven pacing across a 3,000 word essay, these reports show it.
Premium is $10 a month billed yearly ($120 a year), $30 billed monthly, or $399 once for a lifetime license ProWritingAid pricing ↗. The free plan checks grammar, spelling and punctuation, but only 500 words at a time, with 10 rephrases a day ProWritingAid pricing ↗. Yearly and lifetime plans have a 3 day money back guarantee; monthly plans are not refundable ProWritingAid pricing ↗.
Use it for style, and do not rely on it alone for proofreading. In Scribbr's test with 20 planted errors, ProWritingAid fixed 5 and introduced 2 new ones Scribbr grammar checker test ↗. Pair it with a stronger checker, or run your final draft through LanguageTool or Grammarly before you send it.
Why we like ProWritingAid
- More than 25 style and writing reports
- Works in Google Docs and Word
- $399 lifetime license option
- Custom style guide
Where ProWritingAid falls short
- Fixed only 5 of 20 errors in Scribbr's test
- Free plan limited to 500 words at a time
- Monthly plans are not refundable
Hemingway Editor: best for clear, simple writing
Best for anyone whose writing is correct but too long, too passive or hard to read.
Hemingway Editor is about clarity more than commas. The free web version rates how readable your writing is and flags wordy sentences, passive voice and words that have simpler alternatives Hemingway free vs Plus ↗. For a work email or a report summary that people skim, that is often the edit that matters most.
Hemingway Editor Plus adds an advanced grammar checker, AI rewriting and tone and style options Hemingway free vs Plus ↗. The Individual plan is $8.33 a month billed annually ($100 a year) with 5,000 AI sentence rewrites a month, or $12.50 a month ($150 a year) with 10,000 Hemingway Plus ↗. Grammar fixes do not use rewrite credits Hemingway free vs Plus ↗. There is a 2 week free trial with no credit card Hemingway Plus ↗.
If you want to pay once, the Hemingway Editor 3 desktop app is $19.99 for Mac or Windows, works offline and keeps the readability highlights, but the vendor says it does not include the new AI features Hemingway desktop ↗.
Why we like Hemingway Editor
- Free readability highlights in the browser
- Grammar fixes do not use AI credits on Plus
- 2 week trial with no card
- $19.99 desktop app option
Where Hemingway Editor falls short
- Advanced grammar checking needs Plus
- No browser extension listed on the Plus page
- Desktop app lacks the AI features
Compare them
| Tool | Free plan | Paid from | Languages | Works in | Best for |
|---|---|---|---|---|---|
| GrammarlyOur pick | Grammar, spelling, tone, 100 AI prompts/mo | $12/mo billed yearly | Not stated | 1M+ sites and apps, Docs, Office, phones | Everyday writing everywhere |
| LanguageToolBest free option | 2,000 characters per field | €4.99/mo billed yearly | 30+ | Browsers, email apps, Docs, Word, Pages | Multilingual and free use |
| ProWritingAidBest for long reports and essays | 500 words at a time | $10/mo billed yearly; $399 lifetime | Not stated | Google Docs, Word, desktop | Long essays and reports |
| Hemingway EditorBest for clear, simple writing | Readability highlights | $8.33/mo billed yearly | Not stated | Web editor; $19.99 desktop app | Clear, simple writing |
| QuillBot | Unlimited basic checks, no sign up | $8.33/mo billed yearly | English plus 6 others | Web | Quick free checks |
| Wordtune | Unlimited grammar checks, 10 rewrites/day | $4.89/mo billed yearly | Not stated | Not stated on plans page | Sentence rewrites |
Prices and features from each vendor’s site, checked Oct 9, 2026. Prices change often.
Who this is for
This guide is for people who write their own emails, essays, cover letters and reports and want them correct and clear before they hit send. It is a different job from our guides to AI writing tools, which compare tools that generate drafts for you. Here the question is which tool best catches your mistakes and tightens your sentences while leaving your words and voice in place.
That changes what matters. A writing generator is judged on how good its drafts are. A grammar checker is judged on how many real errors it fixes, how many correct sentences it wrongly changes, whether it works inside the app where you already write, and what happens to the text you paste into it.
Students should know that some of these tools now include AI text detection and rewriting. Rewriting whole paragraphs with AI can break school rules even when fixing commas does not, so check your course policy.
How we picked
We read each vendor's pricing and help pages and checked every price on October 12, 2026. We did not run our own error tests; instead we used Scribbr's published test, which pasted the same 160 word text with 20 planted errors into each tool and scored fixes minus new errors Scribbr grammar checker test ↗. Scribbr's own checker is powered by QuillBot through a shared parent company, so we did not count its top score toward QuillBot Scribbr grammar checker test ↗. No vendor paid for placement.
- Errors fixed and errors introduced in an independent test
- Works where you write: browser, email, Google Docs, Word
- Useful free plan, with limits stated plainly
- Languages supported
- Clear privacy terms for the text you check
- Fair yearly price for one person
What a grammar checker can and can't do
It can catch most typos, missing commas, agreement errors and confused words, and the best tools do it as you type. In Scribbr's test, LanguageTool fixed 19 of 20 planted errors and Wordtune 13 Scribbr grammar checker test ↗.
It can also be wrong. ProWritingAid fixed 5 of the 20 errors in that test and introduced 2 new ones Scribbr grammar checker test ↗. Every checker sometimes flags correct sentences, especially names, quotes, technical terms and deliberate style choices. Treat suggestions as questions, not orders.
It cannot check facts or tell whether your argument makes sense. Clarity tools like Hemingway help by flagging long sentences and passive voice Hemingway free vs Plus ↗, but the final read is still yours.
What it costs for one person
On yearly billing, Grammarly Pro is $144 Grammarly Pro cost ↗, ProWritingAid Premium $120 ProWritingAid pricing ↗, Hemingway Editor Plus $100 Hemingway Plus ↗ and LanguageTool Premium €59.89 LanguageTool prices ↗. QuillBot Premium is $8.33 a month billed yearly, about $100 a year QuillBot Premium ↗, and Wordtune Advanced is $4.89 a month billed yearly Wordtune plans ↗.
Monthly billing costs far more: Grammarly and ProWritingAid are both $30 a month Grammarly Pro cost ↗ ProWritingAid pricing ↗. ProWritingAid's $399 lifetime license equals a little over three years of its yearly plan ProWritingAid pricing ↗. If you only need correct emails, the free plans of Grammarly or LanguageTool may be all you need.
Before you sign up
Test with your own writing. Paste a page you know has mistakes into two free plans and compare what each one catches and what it changes that was already right.
Think about what you paste. Contracts, medical notes and student records may fall under your employer's or school's rules. Grammarly lets you opt out of having de identified samples used for product improvement Grammarly privacy ↗, and LanguageTool says browser add on texts are usually not saved LanguageTool Premium ↗. Ask your IT team before using any checker on confidential work.
- Try free plans before paying
- Check where the tool works: browser, Docs, Word, email, phone
- Turn on any training opt out in settings
- Prefer yearly billing only after a month of use
- Read your final draft yourself before sending
The competition
QuillBotFree; Premium $8.33/month billed yearly
QuillBot's free grammar checker needs no sign up and offers unlimited checks in English, German, French, Spanish, Brazilian Portuguese, Swiss German and Dutch QuillBot grammar checker ↗. Premium is $8.33 a month billed yearly and adds advanced grammar suggestions, tone insights and 25,000 words of plagiarism checks a month QuillBot Premium ↗. Its checker scored 20 of 20 in Scribbr's test, but Scribbr's tool is powered by QuillBot, so we did not treat that as independent Scribbr grammar checker test ↗.
WordtuneFree; Advanced starts at $4.89/month billed yearly
Wordtune includes unlimited spelling and grammar checks even on its free plan, but it is mainly a rewriting tool, with 10 rewrites a day free Wordtune plans ↗. Advanced is $4.89 a month billed yearly with a 3 day trial, and the vendor says it does not give refunds Wordtune plans ↗. It fixed 13 of 20 errors in Scribbr's test Scribbr grammar checker test ↗.
Questions people ask
What is the most accurate grammar checker?
In Scribbr's test of 20 planted errors, LanguageTool fixed 19, Wordtune 13, free Grammarly 11 and ProWritingAid 5 while adding 2 new errors Scribbr grammar checker test ↗. Scribbr's own QuillBot powered checker fixed all 20, but Scribbr and QuillBot share a parent company Scribbr grammar checker test ↗. One test is a small sample, so try two tools on your own writing.
Is Grammarly free good enough?
For everyday emails, often yes. Free Grammarly corrects grammar and spelling and shows tone, and it works across more than a million sites and apps Grammarly plans ↗ How Grammarly works ↗. It does not include full sentence rewrites, tone adjustment or plagiarism checks, which need Pro at $12 a month billed yearly Grammarly plans ↗ Grammarly Pro cost ↗.
Is there a better free alternative to Grammarly?
LanguageTool is the best free alternative we found: it supports more than 30 languages and fixed 19 of 20 errors in Scribbr's test, though free checks are limited to 2,000 characters per field LanguageTool Premium ↗ Scribbr grammar checker test ↗. QuillBot's free checker needs no sign up and has no stated word limit QuillBot grammar checker ↗.
Can a grammar checker make my writing worse?
Yes. ProWritingAid introduced 2 new errors in Scribbr's test Scribbr grammar checker test ↗, and every checker can flag correct sentences, names or technical terms. Accept changes one at a time and reread the final version.
Is it safe to put confidential documents into a grammar checker?
Check the privacy terms first. Grammarly says it does not sell your content but may use de identified samples for training unless you opt out Grammarly privacy ↗. LanguageTool says its browser add on usually does not save texts LanguageTool Premium ↗. For legal, medical or student records, ask your employer or school before using any checker.
Which grammar checker is best for non native English speakers?
Grammarly Pro adds fluent English suggestions that go beyond correctness Grammarly plans ↗. If you also write in your first language, LanguageTool checks more than 30 languages in one tool LanguageTool Premium ↗.
Where this comes from
Checked Oct 9, 2026. Vendor pages describe their own products; independent sources add outside views. Built from 14 sources: the makers' own pages plus independent reviews and user reports. We have not run our own hands on test yet; if we do, the results will appear here.
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