What $12/mo Actually Buys
Grammarly's free tier handles the basics: spelling, punctuation, and simple grammar mistakes. Pro unlocks the features that matter -- tone detection across 40+ communication styles, full-sentence rewrites, clarity suggestions, and plagiarism detection. The gap between free and paid is wide enough that the free plan functions more like a trial than a standalone product.
The Enterprise plan (custom pricing, 150+ seats) adds SSO, advanced admin controls, and dedicated support. Pro now includes team features like style guides and brand tones that previously required a separate Business plan.
| Plan | Price | Suggestions | Plagiarism | Generative AI Prompts | Brand Voice |
|---|---|---|---|---|---|
| Free | $0 | Basic grammar/spelling only | No | Limited | No |
| Pro | $30/mo ($12/mo annual) | Full suite (150+ error types) | 16B page database | 2,000/month | Yes, with style guides |
| Enterprise | Custom (150+ seats) | Full suite + admin controls | Yes | Custom | Yes, with team controls |
Compare this to ProWritingAid at $10/mo or QuillBot Premium at $8.33/mo (annual). Grammarly costs more, but neither competitor matches its cross-platform reach.
The Browser Extension Changes the Equation
Most writing tools require copying text into a separate editor. Grammarly flips this by embedding itself into the writing surface already in use -- Gmail, Google Docs, Slack, LinkedIn, Notion, even CMS platforms like WordPress and HubSpot. The extension activates on 500,000+ websites with suggestions appearing inline as text is typed.
This universal presence is the single biggest differentiator. ProWritingAid requires opening its web editor or desktop app for full analysis. QuillBot works primarily through its own interface or a Chrome extension with narrower compatibility. Grammarly's approach means corrections happen where writing happens, not in a separate step.
The mobile keyboard (iOS and Android) extends this to phone-based communication. Autocorrect on steroids, essentially -- catching contextual errors that default phone keyboards miss entirely.
Generative AI: The Rewriting Engine
Grammarly's Generative AI (formerly GrammarlyGO) generates text and rewrites existing content based on natural language prompts. Asking it to "make this email more diplomatic" or "shorten this to 50 words" produces usable results within seconds. Pro subscribers get 2,000 generative AI prompts per month, up from the 1,000 that the old Premium plan offered.
The feature works well for tone adjustment and condensation. Where it struggles: creative rephrasing that preserves a specific authorial voice. The rewrites tend toward a generic professional tone, which is fine for business communication but flattening for marketing copy or editorial content.
Monthly prompt limits apply to all plans, and unused credits do not roll over. Heavy users drafting 20+ emails per day may hit the ceiling before month-end.
vs ProWritingAid: Depth vs Convenience
ProWritingAid offers something Grammarly does not -- deep writing analysis reports. Readability scores, sentence length variation, sticky sentence detection, pacing analysis, and repeated word flagging all appear in detailed report views. For long-form writers producing articles, manuscripts, or research papers, these reports provide genuine editorial value.
Grammarly wins on speed and convenience. Suggestions appear in real time during typing. ProWritingAid's most useful features require running manual reports, which breaks the writing flow. The trade-off is clear: ProWritingAid delivers better analysis for writers willing to step out of their workflow; Grammarly delivers faster corrections for writers who want to stay in theirs.
On pricing, ProWritingAid undercuts at $10/mo with a lifetime license option at $399. Grammarly has no lifetime option.
vs QuillBot: Different Tools for Different Jobs
QuillBot began as a paraphrasing tool and expanded into grammar checking. Its core strength remains rephrasing -- the paraphraser offers 7 modes (Standard, Fluency, Formal, Simple, Creative, Expand, Shorten) that reshape sentences more aggressively than Grammarly's Generative AI.
As a grammar checker, QuillBot falls short. Error detection covers fewer categories, contextual suggestions are less reliable, and the browser extension supports fewer platforms. QuillBot Premium costs $8.33/mo (billed annually), making it the cheapest option among the three, but the grammar checking alone does not justify even that price.
QuillBot works best as a supplementary paraphrasing tool alongside a primary grammar checker. Using it as a Grammarly replacement leaves gaps in error detection and platform coverage.
What's Missing
API access. Zero plans offer API integration. Businesses building custom writing workflows, automated content pipelines, or in-app grammar checking have no path forward with Grammarly. Competitors like Writer.com and Sapling provide API access on enterprise tiers. This gap is significant for any team with development resources.
Creative writing feedback. Grammarly analyzes grammar, tone, and clarity. It does not analyze narrative structure, character voice consistency, dialogue pacing, or plot coherence. Fiction writers, screenwriters, and game writers need tools like ProWritingAid, Sudowrite, or Marlowe for these dimensions.
Offline mode. The browser extension and desktop app require an internet connection for all AI-powered features. Writing on a plane or in a location with poor connectivity means losing access to everything beyond basic spell-check cached locally.
Use Cases Where Grammarly Delivers
High-volume email communication. Sales teams, account managers, and executives sending 30+ emails daily benefit from instant tone and grammar correction without leaving their inbox. The tone detector prevents miscommunication in sensitive threads.
Academic writing with plagiarism requirements. Students submitting papers through Turnitin or similar systems can pre-check originality using Grammarly's 16-billion-page database. The citation suggestions help maintain proper attribution.
Non-native English speakers in professional settings. The contextual grammar engine catches errors that standard spell-checkers miss -- article usage, preposition selection, and idiom accuracy. The explanation feature teaches patterns rather than just correcting them.
Best For / Skip If
Best for:
- Professionals writing across multiple platforms (email, docs, chat, social) daily
- Teams needing consistent grammar and tone standards without manual style guides
- Non-native English speakers who want real-time grammar coaching
- Students needing plagiarism detection bundled with grammar checking
Skip if:
- Building a product that needs grammar checking via API
- Writing fiction, screenplays, or other creative content requiring narrative feedback
- Budget is under $12/mo and ProWritingAid's depth matters more than Grammarly's convenience
- All writing happens in a single app that already has built-in grammar tools
Bottom Line
Grammarly remains the best AI grammar checker and writing assistant for anyone who writes across multiple platforms. The browser extension's universal compatibility creates a safety net that follows the user everywhere, and the Pro plan's tone detection and clarity suggestions go meaningfully beyond basic grammar correction.
The $12/mo annual price ($30/mo if paying monthly) is fair for the coverage. ProWritingAid offers deeper analysis for less money, and QuillBot costs less still, but neither matches Grammarly's integration breadth. The lack of API access and creative writing support are real limitations -- but for professional and academic writing across web applications, nothing else covers as much ground as reliably.