The overlap is real - Grammarly rewrites paragraphs now, Wordtune is half-grammar-checker and half-paraphrase engine, and every major LLM will proofread if you ask it nicely. But the tools in this comparison earn their ranking on corrections per document, precision (not flagging things that are fine), recall (catching the things that are actually wrong), language coverage beyond English, and whether they can operate at enterprise scale without your data becoming a training set.

Quick Rankings

Methodology

I care about three things: does it catch real errors, does it generate noise, and what does it do with your text.

Correction recall and precision are the core metrics. I test each tool against a standard corpus of English-language errors - grammatical mistakes, spelling errors, punctuation violations, subject-verb agreement failures, dangling modifiers - and measure what percentage of real errors are flagged (recall) versus how many suggestions are spurious (precision). A tool that flags 40% of genuine errors but never gives a false positive is not the same product as one that catches 80% of errors with a 30% false-positive rate on clean prose.

Language coverage is the second dimension. Most of these tools were built around English and the non-English support is bolted on. I run checks on French, German, Spanish, Portuguese, Italian, and Polish test documents and note which tools degrade gracefully versus fall off a cliff.

Enterprise privacy posture is the third. I look at whether the vendor uses your text to train models (opt-out vs. opt-in vs. never), whether an enterprise plan provides contractual data isolation, whether you can self-host, and whether SOC 2 / GDPR documentation exists.

False-positive rate matters more than most vendors admit. A grammar checker you stop trusting because it flags your technical jargon, your brand voice, or your intentional stylistic choices is a grammar checker you stop using. Several tools on this list have gotten measurably worse on precision as they have added "AI-powered" suggestions layers on top of their rule-based engines.

The Full Breakdown

1. Grammarly

Grammarly has held the top position in this category for years and still earns it on English-language correction depth. The rule-based engine underneath the AI layer catches what most alternatives miss - comma splices, squinting modifiers, passive voice overuse, inconsistent capitalization, and hundreds of domain-specific usage errors. The browser extension, desktop app, Google Docs integration, and Microsoft Word add-in make it genuinely ubiquitous.

The Business tier adds style guides, a custom dictionary at the organizational level, analytics across team writing, and an API for integrating suggestions into your own applications. SSO and a contractual commitment that your team's text is not used to train their models make it the default choice for legal, finance, and healthcare teams that need grammar checking alongside a reasonable privacy posture.

My gripe with 2025-2026 Grammarly is the false-positive rate on specialized prose. The "clarity" and "engagement" suggestions are frequently wrong on technical writing, academic work, and any content with intentional style choices. The AI rewrite suggestions are a grammar checker pretending to be a writing tool, and the product nudges you toward accepting them even when the original was fine. Turning off "suggestions" beyond the core correctional tier helps, but that requires paying for a tier that then pushes you to use features you are trying to avoid.

The "AI detector" feature bundled into premium plans is marketing. No AI detector has demonstrated reliable accuracy in peer-reviewed evaluation, and Grammarly's implementation is no exception. Ignore it.

What it does: Full-spectrum English grammar, spelling, punctuation, style, and clarity checking. Browser extension, apps, Google Docs, MS Office integrations. Team management and custom style guides at Business tier.

Pricing: Free (basic grammar + spelling only). Premium $12/mo (annual). Business $15/user/mo (annual, 3-seat minimum). Enterprise custom.

Best fit: Teams that write primarily in English and need the deepest corrections coverage with broad integration support.

Honest gotcha: False-positive rate degrades significantly on technical and domain-specific prose. Precision has gotten measurably worse with each AI feature layer added since 2023. Run a precision test on a sample of your actual content before rolling it out - what works fine on marketing copy may be disruptive on engineering documentation.

2. LanguageTool

LanguageTool is the only option I would confidently recommend to non-English writers. The open-source core supports 25+ languages with rule-based engines that reflect actual grammatical scholarship for each language, not English-centric models applied with a translation layer. German, French, Spanish, Portuguese, and Dutch support is notably strong - catching agreement errors and false friends that Grammarly misses entirely.

The self-hosting option is the biggest differentiator for privacy-sensitive deployments. You can run the full LanguageTool server on your own infrastructure, never send a character of your text to an external API, and maintain complete control over the correction corpus. The LanguageTool public API is free for limited volume; the Premium subscription adds access to picky mode, higher API rate limits, and the commercial rule sets. For teams running the self-hosted version, the enterprise license unlocks the premium rules on your own hardware.

The browser extension and API are clean and well-documented. Integration into custom applications is straightforward. On English, the depth trails Grammarly - particularly on style and clarity suggestions - but the core grammar and spelling engine is solid and the false-positive rate is lower because the product has not added an aggressive AI suggestion layer.

What it does: Grammar, spelling, punctuation, and style checking across 25+ languages. Browser extension, MS Word/LibreOffice plugins, API, self-hosted deployment. Open-source core (LGPL).

Pricing: Free (unlimited via extension, limited API). Premium $5.42-19.90/mo (annual) depending on tier. Enterprise: self-hosted license, contact for pricing.

Best fit: Non-English writers, teams with data privacy requirements that preclude cloud APIs, open-source stacks, and multilingual publishing workflows.

Honest gotcha: English style analysis is notably shallower than Grammarly. The free tier's API rate limits make it impractical for high-volume programmatic use - you need Premium or self-hosted for that. The self-hosted setup requires Java and a reasonably capable server; it is not a one-line Docker deploy.

3. ProWritingAid

ProWritingAid is a different category of tool from Grammarly and LanguageTool. Where those tools are real-time correction layers, ProWritingAid is a document analysis platform. You write, paste in your content, and get twenty-something distinct reports: grammar check, style report, overused words, repeated sentence starts, pacing analysis, dialogue tags, cliché detection, consistency check, and more. For fiction writers, this depth is genuinely valuable and unmatched by anything else in this price range.

The grammar engine on English is strong, comparable to Grammarly on correctional accuracy if not on integration breadth. The browser extension works, the Microsoft Word add-in works. What ProWritingAid does not do is compete with Grammarly on integration coverage - there is no native Google Docs support beyond a Chrome extension workaround, and the tool is clearly optimized for desktop writing applications over browser-based workflows.

Privacy posture is reasonable for individuals but I would not deploy it for enterprise teams without reviewing the data retention terms. There is no enterprise tier that provides the kind of contractual data isolation Grammarly Business or LanguageTool self-hosted offer.

What it does: Deep document analysis across 20+ style and grammar reports. Grammar, spelling, style, pacing, and consistency checking. MS Word integration, Scrivener integration, browser extension.

Pricing: Free (limited checks per day, 500 word cap per check). Premium $10/mo (annual). Lifetime $399 one-time.

Best fit: Fiction writers, long-form content creators, and copyeditors who want report-level analysis rather than real-time inline suggestions.

Honest gotcha: Real-time inline checking is slower and less fluid than Grammarly. No SOC 2 certification and no enterprise data isolation tier. Not suitable as a team-wide enterprise deployment for regulated industries.

4. Sapling AI

Sapling occupies the enterprise CRM and support workflow niche. The core product is an AI layer that sits inside Salesforce, Zendesk, HubSpot, Gmail, and similar business communication tools and provides grammar checking, spelling correction, and sentence completion as agents type. For a customer support team of 50 people who write hundreds of tickets per day, the ROI calculation is straightforward: fewer embarrassing errors in customer-facing communication, faster response drafting.

The grammar engine is not the deepest in this comparison on absolute recall, but it covers English well and the 50+ language support is real enough for teams with multilingual support operations. The enterprise tier provides data processing agreements, SSO, and no-training-on-your-data contractual commitments. At $99+/month for team plans, it prices above Grammarly Business per-seat but includes native CRM integrations that Grammarly only approximates through a generic browser extension.

Sapling also includes a sentence autocomplete feature that crosses into AI writing territory, which I list as a gotcha rather than a feature because it blurs what the product does - a grammar checker that also suggests completions is not the same evaluation as a grammar checker that only corrects.

What it does: Real-time grammar, spelling, and style corrections embedded in CRM, support, and email tools. 50+ language support. Snippet manager and sentence autocomplete. Enterprise SSO and DPA.

Pricing: Free (limited). Pro $25/mo (individual). Team $99+/mo (contact sales for volume). Enterprise custom.

Best fit: Customer support teams, sales ops, and any organization writing large volumes of customer-facing communication inside business software tools.

Honest gotcha: Autocomplete feature adds AI writing capability that is not the core value proposition - be deliberate about whether you want agents using it. Grammar depth on English trails Grammarly on the long tail of style and clarity suggestions.

5. DeepL Write

DeepL Write is covered in the Best AI Translation Tools roundup as a writing feature of the DeepL platform, but it earns a standalone mention here because for non-English grammar correction - particularly German, French, Spanish, Italian, Portuguese, and Dutch - it is competitive with or better than most tools on this list.

The product surfaces grammar and style suggestions within the DeepL interface and positions them as alternative phrasings rather than flagged errors, which is a more useful UX for fluent speakers who want style improvement rather than error correction. GDPR compliance, a contractual no-training commitment on paid plans, and EU data residency make it a natural fit for European organizations already in the DeepL ecosystem.

On English, the depth is below Grammarly and ProWritingAid. On the seven languages it covers, the quality of suggestions for non-native speakers and native speakers alike is notably better than bolted-on multilingual support from competitors.

What it does: Grammar and style correction in 7 languages (EN, DE, FR, ES, PT, IT, NL) via the DeepL Write interface and API. Integrated with DeepL translation workflows.

Pricing: Free tier (limited). DeepL Pro Starter $10.49/mo (annual). Advanced $34.99/mo. Ultimate $59.49/mo. Business from $119.99/mo.

Best fit: European teams writing in German, French, Spanish, or Portuguese who need grammar correction alongside translation. Anyone already paying for DeepL Pro gets Write included.

Honest gotcha: Only 7 languages. No browser extension for arbitrary web-based writing. English grammar depth is below the dedicated tools in this comparison.

6. Wordtune

Wordtune started as a sentence rewriter and added grammar checking rather than the other way around, and the product reflects that origin. The grammar and spelling correction is solid on English but not deep - it catches the obvious errors but misses the subtle ones that Grammarly or ProWritingAid would flag. What it does well is sentence-level rewriting with style awareness: make this more formal, shorter, casual, or different while keeping the meaning.

At $9.99/month individual, the price is reasonable. The free tier is more generous than most alternatives. The browser extension works well in Google Docs, Gmail, and most web-based text fields. There is no meaningful enterprise tier with data isolation commitments, which limits its deployment in regulated industries.

What it does: Real-time grammar checking and sentence rewriting for English. Browser extension for Google Docs, Gmail, and web-based text. Tone adjustment suggestions.

Pricing: Free (10 rewrites/day, limited grammar). Plus $9.99/mo (annual). Unlimited $14.99/mo.

Best fit: Individual writers who want grammar correction plus light rewriting in a single lightweight browser tool. Marketing and communications teams working primarily in web-based apps.

Honest gotcha: Grammar recall on English is below Grammarly and ProWritingAid - it misses complex errors. No enterprise privacy tier. English only for meaningful correction quality.

7. Microsoft Editor

Microsoft Editor is the grammar checker you get for free if you have a Microsoft 365 subscription, which means most enterprise workers already have access to it. The free browser extension also works outside Office - it surfaces in Gmail, Google Docs, and most web text inputs.

Correctional quality on English is decent but not deep - comparable to early Grammarly rather than current Grammarly. The 20+ language support works reasonably well for spelling and basic grammar in European languages. The enterprise privacy story is effectively the same as M365 - your text goes through Microsoft's systems under standard enterprise data processing terms.

For teams that need basic grammar checking without a new vendor relationship, Microsoft Editor is good enough and already paid for. For teams that write substantial amounts of important content and need deep correction quality, it is not adequate.

What it does: Grammar, spelling, style, and clarity suggestions in English (deeply) and 20+ languages (shallowly). Integrated into MS Word, Outlook, Teams, and available as a browser extension.

Pricing: Free (browser extension). Included in Microsoft 365 Personal/Family ($6.99-9.99/mo) and M365 Business ($6-22/user/mo).

Best fit: M365-centric organizations that need a baseline grammar check across communication tools without an additional vendor relationship.

Honest gotcha: Correction depth does not match Grammarly or ProWritingAid for English. The "Refinements" suggestions (conciseness, vocabulary, formality) are useful for casual prose but generate noise on technical writing.

8. Writer.com

Writer is an enterprise writing platform that bundles grammar checking alongside company-specific style guide enforcement, terminology management, and brand voice consistency. The grammar engine is not its primary differentiator - what Writer does that none of the other tools here do is let you define your own rules at the organization level and enforce them at the point of writing.

If your company has a house style that says never use passive voice, always capitalize "Platform" as a product name, and prefer "customer" to "user" - Writer enforces that in real time, company-wide, with admin controls and analytics on compliance. For legal and compliance teams that need terminology accuracy enforced at scale, that capability justifies the price.

The per-user cost ($18+/user/month) is the highest in this comparison, and the product makes most sense at 20+ user deployments where brand consistency actually requires a system to enforce it. Note that the grammar checking alone does not justify the price - you are buying the brand governance platform, of which grammar checking is one component.

What it does: Grammar and spelling checking plus custom style guide enforcement, terminology management, and brand voice rules. Enterprise SSO, DPA, and admin controls.

Pricing: Team $18/user/mo (annual, minimum seats apply). Enterprise custom.

Best fit: Large enterprises with established house style guides, regulated industries with terminology requirements, and content-heavy organizations where brand voice consistency across dozens of writers matters.

Honest gotcha: Significant overkill for teams without complex style governance needs. Grammar-checking-only buyers will find better value at lower cost from Grammarly Business. The product works best when you invest in building out your style guide rules, which takes meaningful upfront time.

9. Hemingway Editor

Hemingway Editor is not really a grammar checker. It does not catch grammatical errors in the traditional sense - it does not flag subject-verb disagreement or comma splices. What it does is enforce readability: it highlights long sentences, very long sentences, adverbs, passive voice, and phrases with simpler alternatives, and grades your text on Flesch-Kincaid reading level.

For writers who need to hit a specific reading level - government communications, consumer-facing healthcare content, educational materials - Hemingway's enforcement is ruthless and useful. For everyone else, treating its highlights as mandates rather than considerations is a category error.

The web editor is free, the desktop app is a one-time $19.99 purchase, and no text is ever sent anywhere - the desktop version works completely offline. That privacy posture is unmatched in this comparison for teams with strict data handling requirements who primarily need readability control rather than deep grammar correction.

What it does: Readability analysis - highlights complex sentences, adverbs, passive voice, and difficult phrases. Assigns Flesch-Kincaid grade level. No grammar checking in the traditional sense.

Pricing: Free (web). Desktop app $19.99 one-time.

Best fit: Writers targeting specific reading levels, plain-language compliance workflows, and teams writing consumer-facing or regulatory communications.

Honest gotcha: Not a substitute for a real grammar checker. Heavy usage for all prose regardless of context produces worse writing - technical and academic content legitimately requires complex sentences and precise vocabulary that Hemingway will flag as problems.

10. Trinka AI

Trinka is purpose-built for academic and scientific writing and it shows. The correction engine has been trained on academic corpora and understands discipline-specific conventions - passive voice is fine in methods sections, hedging language is intentional in results sections, and Latin abbreviations like "et al." and "viz." are not errors. Grammarly flags all of these; Trinka does not.

The plagiarism check, journal recommendation, and consistency check for scientific terminology are genuinely useful features for researchers. The "Advanced Suggestions" mode improves technical precision in ways that general-purpose grammar checkers cannot.

At $80/year individual, Trinka is reasonably priced for researchers. The institutional license structure makes it deployable at universities. The limitation is scope - outside academic and scientific writing, the correction depth is below Grammarly and ProWritingAid.

What it does: Academic and scientific writing - grammar, style, consistency, and technical terminology checking calibrated for research writing. Plagiarism check. Journal recommendation.

Pricing: Free (limited). Premium $80/year. Institution license custom.

Best fit: Researchers, academics, and scientific writers who need a grammar checker that understands their genre conventions rather than fighting them.

Honest gotcha: Significantly weaker outside academic writing contexts. The false-positive reduction comes from training on a narrow corpus - general business or creative writing gets worse coverage. No meaningful enterprise privacy commitments for non-institutional plans.

11. QuillBot Grammar Checker

QuillBot's grammar checker is the free component of a platform that leads on paraphrasing and summarization. On grammar correction, it is functional but shallow - it catches obvious errors and handles basic spelling, but the recall on complex grammatical errors is below the top tools in this comparison.

The browser extension is lightweight and works in most web-based text fields. For users who are already in the QuillBot ecosystem for paraphrasing, using the bundled grammar checker is a reasonable choice. As a standalone grammar tool, it does not outperform free-tier Grammarly on English, and there is no meaningful non-English support.

What it does: Basic grammar and spelling checking for English. Browser extension. Integrated with QuillBot paraphrasing and summarization tools.

Pricing: Free (with usage limits on other QuillBot features). Premium $8.33/mo (annual) unlocks the full platform.

Best fit: Users already using QuillBot for paraphrasing or summarization who want basic grammar correction in the same interface.

Honest gotcha: Grammar recall on complex errors is below Grammarly Free, which costs the same (free). Use this if you are paying for QuillBot Premium for paraphrasing features - not as a primary grammar tool.

12. Ginger Software

Ginger has a 40+ language claim and an ESL-learner focus that distinguishes it from most tools here. The translation-integrated correction - where you can see a corrected sentence alongside a translation into your native language to understand why the correction was made - is genuinely useful for language learners in a way that purely prescriptive correction is not.

On English grammar depth, Ginger is below Grammarly and ProWritingAid. The product has not received the kind of AI-layer upgrades that competitors have in 2024-2025, and it shows in recall on subtle errors. For enterprise or team deployment, there is no meaningful privacy posture documentation.

What it does: Grammar, spelling, and punctuation correction with translation support for ESL learners. 40+ language interface.

Pricing: Free (limited). Monthly from $13.99.

Best fit: ESL learners and non-native English writers who benefit from native-language explanation of corrections.

Honest gotcha: English correction depth has fallen behind the market. No meaningful enterprise deployment option.

Tools I Considered and Declined to Rank

WhiteSmoke was a competitive product in 2018. The rule set has not kept pace with the market and the pricing is no longer competitive with free-tier Grammarly or LanguageTool. Not worth spending money on in 2026.

PaperRater is a free student tool with basic grammar checking and an originality report. The correction depth is minimal. Fine as a no-cost sanity check for students, not suitable for professional writing workflows.

Instatext focuses on academic register improvement rather than error correction - it rewrites for formality and precision. Worth knowing if that specific use case applies, but not a grammar checker in the primary sense.

Enterprise Privacy - What to Actually Ask

If you are evaluating these tools for a team, here is what to ask before signing:

1. Is my text used to train models? Grammarly Business has an opt-out. LanguageTool self-hosted is never in scope. Writer.com has enterprise DPA. DeepL Write has a contractual no-training commitment on paid plans. QuillBot, Wordtune, and Ginger do not have documented enterprise commitments.

2. Do you have SOC 2 Type II? Grammarly (yes), Writer.com (yes), Sapling (yes, enterprise tier), Microsoft Editor (covered under M365 SOC 2). Most others: no.

3. Where does my text go when I use the browser extension? Every cloud-based grammar checker sends your text to their API. If you are checking confidential contracts, legal filings, or clinical notes, you need either a self-hosted tool (LanguageTool), a platform with a signed BAA or equivalent (Grammarly Business, Sapling Enterprise), or a fully offline tool (Hemingway Desktop for readability only).

4. What is the price per user at 100 seats? Grammarly Business at $15/user/mo is $1,500/mo for 100 seats. LanguageTool Premium for teams is significantly cheaper. Writer.com enterprise pricing is negotiated; expect $18-25/user/mo at scale. At 500+ seats, the delta between Grammarly and LanguageTool becomes material.

Best Pick by Use Case

English-only team, deepest coverage - Grammarly Business. Disable the AI rewrite suggestions and use it as a pure correction layer.

Non-English or multilingual team - LanguageTool Premium or self-hosted. There is no real competitor here for French, German, Spanish, and Portuguese depth.

Academic or scientific researchers - Trinka AI. The false-positive reduction on academic conventions justifies the narrower scope.

Fiction or long-form prose - ProWritingAid. The report depth on style, pacing, and consistency is unmatched.

Customer support or CRM teams - Sapling AI. Native integrations with Salesforce, Zendesk, and HubSpot make it the obvious choice for this workflow.

Privacy-first, no cloud - Hemingway Desktop for readability (fully offline), plus LanguageTool self-hosted for grammar. The combination covers both layers without sending text anywhere.

Already on DeepL for translation - DeepL Write is included in paid plans and handles non-English grammar well. Worth using before adding another vendor.

M365 enterprise, budget constrained - Microsoft Editor is already paid for and good enough for basic checking across the organization's communication tools.

Sources

• Grammarly Business - Features and Pricing
• LanguageTool Premium - Pricing and API
• ProWritingAid - Product Overview
• Sapling AI - Grammar Check and CRM Integration
• DeepL Write
• Wordtune
• Microsoft Editor - Features
• Writer.com
• Hemingway Editor
• Trinka AI - Academic Writing
• QuillBot Grammar Check
• Ginger Software