The 10 Best AI Tools for Grammar and Proofreading in 2027
Curated by Kory White · Fractional CRO, CRO SyndicateA grammar and proofreading AI tool catches the mistakes you stop seeing after the third reread: comma splices, dropped articles, tense drift, and the awkward phrasing that makes a confident draft read like a rough one. The best of them go further, rewriting clunky sentences, flagging plagiarism, and adapting to the tone a marketing email needs versus a legal memo.
This list ranks the ten tools that actually earn a spot in your writing workflow in 2027, with real plan prices and an honest read on where each one wins.
Direct Answer
For most people who write professionally, Grammarly is the Best Overall AI grammar and proofreading tool in 2027. It combines a strong correctness engine with full-rewrite suggestions, tone detection, and a browser extension that works in Gmail, Google Docs, Slack, and almost any text field.
The free tier handles core grammar and spelling; Grammarly Premium runs $12/month billed annually (about $30 month-to-month), and Grammarly Business starts around $15/user/month.
The Best Value pick is LanguageTool, an open-source-rooted checker that supports 30+ languages and offers a genuinely useful free tier. LanguageTool Premium is $4.92/month on the annual plan, roughly a third of Grammarly's price, with a self-hostable engine that privacy-conscious teams can run on their own servers.
This list is for writers, students, marketers, support agents, non-native English speakers, and anyone who edits more than they draft. If you want raw correction power, depth of style coaching, multilingual support, or the cheapest path to clean copy, there's a pick below for you.
How We Ranked the Top 10
We scored every tool against six weighted criteria, drawing on G2 and Capterra review averages, official pricing pages, and head-to-head error-detection tests writers and reviewers publish each year.
- Correction accuracy (30%) — how many real errors it catches and how few false positives it raises on edge-case grammar.
- Rewrite and style quality (20%) — clarity, conciseness, and tone suggestions, not just red underlines.
- Price and value (15%) — free-tier usefulness and what the paid tiers actually cost.
- Integrations and reach (15%) — browser extensions, Word/Google Docs add-ins, mobile keyboards, and API access.
- Languages and scope (10%) — multilingual support and specialized checks like plagiarism.
- Privacy and control (10%) — data handling, training opt-out, and self-hosting options.
Scores were normalized to a 100-point scale; the ranking below reflects the totals.
1. Grammarly 🏆 BEST OVERALL
Best for: all-around grammar, tone, and rewriting | Pricing: Free / $12/mo Premium (annual) | Platform: web, desktop, browser extension, mobile keyboard
Grammarly remains the most complete writing assistant in 2027, pairing a mature correction engine with generative rewrites powered by its own large language models. The free plan covers grammar, spelling, and basic punctuation, while Premium at $12/month unlocks full-sentence rewrites, tone adjustment, clarity scoring, and a plagiarism checker against billions of web pages.
Its browser extension is the real differentiator, working inside Gmail, Google Docs, LinkedIn, Slack, and nearly any web text box, plus native add-ins for Microsoft Word and a macOS/Windows desktop app. Grammarly Business adds a brand-tone style guide and analytics for around $15/user/month, and the company lets enterprise customers opt out of having their text used for model training.
Pros:
- Best-in-class correction accuracy with low false-positive rates
- Works almost everywhere through its browser extension and desktop apps
- Generative rewrites and tone detection beyond simple error flags
- Built-in plagiarism checker on the Premium tier
Cons:
- English-only (no real multilingual support)
- Premium is among the pricier options at full month-to-month rate
Verdict: The default choice for anyone who wants strong corrections and rewriting in one polished package.
2. ProWritingAid
Best for: long-form writers, authors, and deep style editing | Pricing: Free (limited) / $10/mo Premium (annual) | Platform: web, desktop, browser extension, Word/Scrivener add-ins
ProWritingAid is the editor's editor, built for novelists, academics, and anyone working on long documents. Beyond grammar, it produces 25+ in-depth reports covering pacing, sticky sentences, overused words, repeats, sentence-length variety, and readability. Premium runs about $10/month annually (or a one-time lifetime license around $399), and a Premium Pro tier adds an AI rewrite layer.
Its standout feature is the deep Scrivener integration plus add-ins for Microsoft Word, making it a favorite for manuscript-length work where Grammarly's web-first model feels thin. The free plan limits you to short documents, so serious users will need the paid tier.
Pros:
- Deepest style and structure analysis of any tool here
- One-time lifetime license option avoids subscriptions
- Scrivener and Word integration for book-length projects
- Detailed reports teach you to write better, not just fix errors
Cons:
- Interface and report volume can overwhelm casual users
- Grammar engine is slightly behind Grammarly on raw accuracy
Verdict: The top pick for authors and long-form writers who want editing depth over quick fixes.
3. LanguageTool 💎 BEST VALUE
Best for: multilingual writers and privacy-minded teams | Pricing: Free / $4.92/mo Premium (annual) | Platform: web, browser extension, Word/Google Docs add-ins, self-hosted
LanguageTool delivers the best value in this list by a wide margin. It checks grammar, style, and spelling across 30+ languages including English, German, Spanish, French, and Dutch, and its free tier is genuinely usable for everyday text. Premium is just $4.92/month annually, well under half what most rivals charge, and unlocks longer text limits, advanced style suggestions, and a personal dictionary.
Crucially, the engine is open-source-rooted and self-hostable, so security-conscious companies can run it on their own infrastructure with no text leaving their network. It offers extensions for Chrome, Firefox, Edge, plus add-ins for Word and Google Docs.
Pros:
- 30+ language support that rivals can't match
- Lowest paid price at roughly $5/month
- Self-hosting option for full data control
- Strong free tier that covers most casual needs
Cons:
- English rewrites are less fluent than Grammarly's
- No plagiarism checker
Verdict: The best value and the obvious choice for multilingual writers or anyone who needs to keep data in-house.
4. QuillBot
Best for: paraphrasing, summarizing, and rewording | Pricing: Free / $9.95/mo Premium (annual) | Platform: web, browser extension, Word add-in
QuillBot started as a paraphrasing tool and grew into a full writing suite that now includes a solid grammar checker, summarizer, plagiarism detector, and citation generator. Its paraphrasing modes (Standard, Fluency, Formal, Creative, and more) are the best in the category for rewording sentences while preserving meaning, which makes it popular with students and ESL writers.
The free plan caps paraphrasing at 125 words at a time; Premium at $9.95/month annually removes limits and adds tone and plagiarism features. QuillBot was acquired by Course Hero (Learneo) and integrates cleanly into Word and the major browsers.
Pros:
- Best-in-class paraphrasing engine with multiple modes
- All-in-one suite: rewrite, summarize, cite, and check grammar
- Affordable Premium under $10/month
- Built-in plagiarism checker on paid plans
Cons:
- Grammar checking is secondary to paraphrasing
- Free tier word limits are restrictive
Verdict: The pick when rewording and paraphrasing matter as much as catching errors.
5. Hemingway Editor
Best for: clarity, concision, and readability | Pricing: $19.99 one-time (desktop) / $10/mo Plus | Platform: web, desktop
Hemingway Editor doesn't fix commas; it makes your writing punchier. It color-codes hard-to-read sentences, passive voice, adverbs, and overly complex phrasing, then assigns a readability grade level so you can simplify until the prose lands. The classic desktop app is a $19.99 one-time purchase with no subscription, while the newer web-based Hemingway Editor Plus at about $10/month adds AI-powered rewrites that automatically fix the highlighted issues.
It's the best tool here for tightening bloated copy, though it's deliberately narrow and won't catch subtle grammar errors the way Grammarly does.
Pros:
- Brilliant at concision and cutting wordiness
- One-time desktop purchase with no recurring fee
- Readability grading keeps writing accessible
- AI rewrites on the Plus plan fix flagged sentences
Cons:
- Weak as a pure grammar/spelling checker
- No browser extension on the classic app
Verdict: The best tool for making good writing tighter and clearer, paired with a stronger grammar checker.
6. Microsoft Editor
Best for: Microsoft 365 users who want built-in checking | Pricing: Free / included with Microsoft 365 ($6.99/mo Personal) | Platform: Word, web, browser extension
Microsoft Editor is the quiet bargain baked into the apps millions already pay for. The free version offers grammar and spelling in Word, Outlook, and via a browser extension; the advanced suggestions (clarity, conciseness, formality, and a similarity/plagiarism checker) come bundled with any Microsoft 365 subscription starting at $6.99/month.
It supports 20+ languages and uses Microsoft's AI models to power rewrites that now rival third-party tools. If you live in Word and Outlook, you may not need a separate subscription at all, which is exactly why it ranks this high despite a thinner standalone experience.
Pros:
- Free with any Microsoft 365 plan you likely already own
- Native to Word and Outlook with no extra setup
- Multilingual support across 20+ languages
- Similarity checker for catching unoriginal text
Cons:
- Best features are gated behind a Microsoft 365 subscription
- Browser extension is less capable than Grammarly's
Verdict: A no-brainer if you already pay for Microsoft 365 and write mostly in Office apps.
7. Wordtune
Best for: rewriting for tone and flow | Pricing: Free / $6.99/mo Advanced (annual) | Platform: web, browser extension, Word add-in
Wordtune, built by AI21 Labs, focuses on rephrasing rather than red-pen correction. Highlight any sentence and it offers multiple rewrites that shift tone between casual and formal, shorten or expand the text, and smooth awkward phrasing. The free plan allows a limited number of rewrites per day; Advanced at $6.99/month annually lifts the cap and adds tone controls, a summarizer (Wordtune Read), and AI text generation.
It's a strong companion for non-native speakers who understand grammar rules but struggle with natural-sounding English, and its browser extension works well across Gmail and most web editors.
Pros:
- Excellent natural-sounding rewrites for tone and flow
- Affordable at under $7/month
- Summarizer and AI writing included on paid plans
- Helpful for ESL writers who want fluent phrasing
Cons:
- Free daily rewrite limits are tight
- Lighter on hard grammar correction than dedicated checkers
Verdict: A great rewriting partner when phrasing matters more than catching mechanical errors.
8. Ginger
Best for: contextual correction and sentence rephrasing | Pricing: Free / ~$13.99/mo Premium | Platform: web, desktop, browser extension, mobile keyboard
Ginger has been correcting grammar for over a decade and leans on contextual sentence rephrasing to catch errors other spell-checkers miss, like the difference between "their" and "there" based on surrounding words. Premium runs about $13.99/month (cheaper on longer terms) and includes a sentence rephraser, a text-to-speech reader, and a personal trainer that quizzes you on your common mistakes.
It also offers translation across 40+ languages, which makes it useful for ESL writers. Ginger's apps span Windows, macOS, iOS, and Android keyboards, though its interface feels dated next to newer rivals.
Pros:
- Strong contextual error detection for confusable words
- 40+ language translation built in
- Text-to-speech and learning tools to improve over time
- Wide platform coverage including mobile keyboards
Cons:
- Dated interface compared to modern tools
- Premium pricing is on the higher side for its feature depth
Verdict: A solid contextual corrector with handy translation, best for learners polishing their English.
9. Writer
Best for: teams enforcing brand voice and compliance | Pricing: Team from ~$18/user/mo / Enterprise custom | Platform: web, browser extension, Word/Google Docs add-ins, API
Writer is the enterprise pick, built to keep large teams consistent rather than to fix a student's essay. It enforces a company style guide, approved terminology, and brand voice across every document, flagging off-brand phrasing, banned terms, and inconsistent capitalization in real time.
Team plans start around $18/user/month, with custom Enterprise pricing that adds an API, SSO, and a self-hosted LLM option so regulated industries keep data private. It's overkill for individuals, but for marketing, support, and content teams that need everyone writing the same way, nothing else here competes on governance.
Pros:
- Enforces brand voice and terminology at scale
- API and SSO for enterprise deployment
- Strong data privacy with no-training guarantees
- Real-time compliance flags for regulated content
Cons:
- Priced and built for teams, not individuals
- No free tier for personal use
Verdict: The right tool for organizations that need consistent, on-brand, compliant writing across a whole team.
10. ChatGPT
Best for: flexible, prompt-driven proofreading and rewriting | Pricing: Free / $20/mo Plus | Platform: web, desktop, mobile, API
ChatGPT isn't a dedicated grammar checker, but in 2027 it's a remarkably capable one when prompted well. Paste a paragraph and ask it to fix grammar, tighten the prose, or match a specific tone, and it returns a clean rewrite with optional explanations of each change. The free tier runs on capable models, while Plus at $20/month unlocks the strongest reasoning models, faster responses, and longer context for editing entire documents.
Its weakness as a proofreader is the flip side of its strength: it may rewrite more than you asked or occasionally introduce a change you didn't want, so it lacks the precise, underline-this-word control of a purpose-built checker.
Pros:
- Endlessly flexible for any editing or rewriting request
- Explains its corrections when you ask it to
- Handles whole documents with long context on Plus
- Already in most people's toolkit for other tasks
Cons:
- No inline, click-to-accept correction interface
- Can over-edit or alter meaning if not prompted carefully
Verdict: A powerful all-purpose editor for those comfortable prompting, but less precise than a dedicated checker.
Which One Is Right for You?
What to Look For
- Free vs paid: Test the free tier first. LanguageTool, Grammarly, and Microsoft Editor all catch core errors free; pay only when you need rewrites, tone control, or plagiarism checks.
- Data privacy and training opt-out: Confirm whether your text trains the vendor's models. Writer and enterprise Grammarly offer no-training guarantees, and LanguageTool can be self-hosted so nothing leaves your network.
- Export and licensing rights: If a tool rewrites your work, make sure you own the output outright. All the picks here grant you full rights to corrected text, but always read the terms.
- Integration with your stack: A checker only helps where you write. Verify it has an extension or add-in for Word, Google Docs, Gmail, or wherever your words actually go.
- Output limits and accuracy trade-offs: Watch for word caps on free tiers and false positives. A tool that over-flags wastes more time than it saves.
What matters less than the hype is the headline AI model name. The tool that fits your actual writing surface and budget will help you more than the one with the flashiest model under the hood.
FAQ
What is the best free AI grammar checker in 2027? LanguageTool has the most generous free tier with 30+ language support, while Grammarly Free and Microsoft Editor both cover core English grammar and spelling at no cost. For most users, the free version of one of these three is enough for everyday writing.
Is Grammarly worth paying for? If you write professionally and want full-sentence rewrites, tone detection, and a plagiarism checker, Grammarly Premium at $12/month (annual) is worth it. Casual writers who only need basic error correction can stay on the free plan or use LanguageTool instead.
Which tool is best for non-native English speakers? Wordtune and QuillBot shine for ESL writers because they rephrase sentences into natural-sounding English, and Ginger adds translation across 40+ languages. LanguageTool is also strong if you write in multiple languages day to day.
Can ChatGPT replace a dedicated grammar checker? It can for flexible, prompt-driven editing, but it lacks the precise inline correction interface of Grammarly or ProWritingAid and may rewrite more than you intended. Many writers use ChatGPT for heavy rewrites and a dedicated checker for clean, controlled proofreading.
Do these tools check for plagiarism? Grammarly Premium, QuillBot Premium, and Microsoft Editor (with Microsoft 365) include plagiarism or similarity checking. ProWritingAid offers it as a paid add-on. LanguageTool and Hemingway Editor do not.
Which tool is best for writing a book? ProWritingAid is the strongest choice for long-form work thanks to its deep style reports and native Scrivener integration, with a one-time lifetime license that avoids ongoing subscription costs.
Bottom Line
For most writers, Grammarly is the Best Overall AI grammar and proofreading tool in 2027, pairing top-tier accuracy with rewrites and tone detection across nearly every app you write in; the free tier is solid and Premium is $12/month annually. If price or multilingual support drives your choice, LanguageTool is the Best Value at $4.92/month with 30+ languages and a self-hostable engine.
Match the tool to where you write and what you write, and any pick on this list will leave your copy cleaner than you left it.
Sources
- Grammarly official pricing
- ProWritingAid pricing
- LanguageTool premium plans
- QuillBot pricing
- Hemingway Editor
- Microsoft Editor
- Wordtune plans
- Writer.com pricing
*AI tools for grammar review — best AI for grammar and proofreading, grammar checker AI reviews, ratings, best AI proofreading tools 2027, and a review of the top picks.*