Grammarly vs ProWritingAid vs Hemingway vs LanguageTool 2025: Best AI Grammar Checker Compared

AI grammar checkers have evolved far beyond spell-check into comprehensive writing assistants that improve clarity, style, tone, and engagement. The four leading options each serve different writing needs and budgets. This guide helps you choose the right tool for your writing workflow.

Quick Comparison

Grammarly — Best Overall Writing Assistant

Grammarly is the most widely used AI writing assistant with over 30 million daily users. It catches grammar errors, suggests style improvements, adjusts tone, and now includes GrammarlyGO—a generative AI feature that can compose, rewrite, and brainstorm content. Its ubiquity across platforms (browser, desktop, mobile, Microsoft Office) makes it the most convenient choice.

Key Features

• Grammar and spelling — industry-leading error detection across all contexts
• GrammarlyGO — AI writing, rewriting, brainstorming, and tone adjustment
• Tone detection — real-time feedback on how your writing sounds to readers
• Clarity suggestions — simplify complex sentences and improve readability
• Plagiarism checker — compare against billions of web pages (Premium)
• Style guide — enforce organization-specific writing rules (Business)
• Works everywhere — browser extension, desktop app, mobile keyboard, Office integration

Pricing

• Free: Basic grammar, spelling, punctuation
• Premium ($12/month, annual): Clarity, style, tone, plagiarism, GrammarlyGO
• Business ($15/member/month): Style guide, admin controls, analytics

ProWritingAid — Best for Long-Form Writers

ProWritingAid provides the deepest writing analysis of any tool. Beyond grammar checking, it offers 20+ reports on style, pacing, readability, sentence structure, repeated words, and more. It’s the preferred tool for novelists, academic writers, and anyone who produces long-form content and wants to systematically improve their craft.

Key Features

• 20+ analysis reports — style, readability, overused words, sentence variety, pacing, consistency
• Word Explorer — thesaurus, collocations, alliterations, cliches
• Scrivener integration — works directly in the popular book-writing tool
• Writing style comparisons — compare your style to published authors
• AI writing assistant — generate, rewrite, and expand content
• Plagiarism checker — academic-grade plagiarism detection (Premium)

Pricing

• Free: 500-word limit per check, basic suggestions
• Premium ($10/month, annual): Unlimited, all 20+ reports
• Lifetime ($399, one-time): Best value for long-term users

Hemingway Editor — Best for Readability

Hemingway takes a focused approach: it makes your writing bold and clear. Color-coded highlights show complex sentences (yellow), very hard-to-read sentences (red), passive voice (green), adverbs (blue), and simpler alternatives (purple). The latest version adds AI writing and rewriting features while maintaining its signature simplicity.

Key Features

• Readability grade — instant readability score (target: Grade 9 or below)
• Color-coded feedback — visual highlights for different writing issues
• AI writing — generate and rewrite text with AI (new feature)
• Distraction-free editor — clean, focused writing interface
• Desktop app — works offline with no cloud processing

Pricing

• Web (free): Full readability analysis in browser
• Desktop + AI ($10/month or $100 one-time): Offline use, AI features

LanguageTool — Best Free and Multilingual Option

LanguageTool is an open-source grammar checker that supports 30+ languages—making it the clear choice for non-English writers. It offers a self-hosted option for maximum privacy and a generous free tier. While not as feature-rich as Grammarly, it catches most grammar errors and is continuously improving.

Key Features

• 30+ languages — the most multilingual grammar checker available
• Open source — self-hosted option for maximum privacy
• Browser extension — works in Chrome, Firefox, Edge, Safari
• Microsoft Office add-in — integration with Word and Outlook
• Picky mode — stricter checking for professional writing (Premium)
• Style suggestions — basic clarity and style improvements (Premium)

Pricing

• Free: 10,000 characters per check, basic grammar
• Premium ($5/month, annual): Longer texts, style suggestions, picky mode
• Team ($8/member/month): Admin dashboard, priority support

Which Grammar Checker Should You Choose?

For everyday professional writing

→ Grammarly Premium ($12/mo). The broadest coverage across platforms, best tone detection, and GrammarlyGO for AI writing make it the most versatile choice for business professionals.

For book authors and long-form writers

→ ProWritingAid ($10/mo or $399 lifetime). The 20+ writing analysis reports provide insights that help you systematically improve your craft. Scrivener integration is a major plus for novelists.

For making writing concise and clear

→ Hemingway (free web version). If your main goal is reducing complexity and improving readability, Hemingway’s focused approach is unmatched. Use the free web version before considering the desktop app.

For non-English writing

→ LanguageTool ($5/mo or free). The only option with strong grammar checking in 30+ languages. The self-hosted option is ideal for privacy-sensitive organizations.

On a tight budget

→ LanguageTool (free) + Hemingway (free web). This combination covers grammar checking and readability analysis at zero cost.