Criterion Grammarly QuillBot
CategoryAI Writing & Content CreationAI Writing & Content Creation
In one sentenceAn AI writing assistant that checks grammar, tone and clarity wherever you type and can rewrite or generate text on request.A suite of writing tools for paraphrasing, summarising, grammar checking and AI detection, popular with students.
Problem it solvesEveryday writing such as emails, reports and essays often contains errors or unclear phrasing, and checking it manually is slow.Rewording, condensing or checking text by hand is slow, especially for students and non-native writers.
Free planYesYes
Developer APIYesNo
Open sourceNoNo
PlatformsWeb, Browser extension, Windows, macOS, Microsoft Word, Google DocsWeb, Browser extension, Microsoft Word, Google Docs
Pricing (summary)Free plan with basic corrections and 100 AI prompts per month. Pro costs $30 billed monthly, $60 per quarter, or $144 per year ($12/month), per member. Enterprise is priced through sales.
Checked 2026-10-19		Free tier with word limits. Premium is shown at $8.33/month billed annually ($99.95/year); QuillBot's FAQ lists $19.95 for monthly billing. Team plans start at $7.50 per seat per month for 2-10 seats. Prices can vary by region.
Checked 2026-10-19
Strengths
  • Works across many apps without copy-pasting
  • Low learning curve
  • Generous free tier for basic correction
  • Generous free tier
  • Low-cost annual plan
  • Simple interface
Limitations
  • Free plan limited to 100 AI prompts per month
  • Advanced rewriting and plagiarism checks need Pro
  • No public general-purpose writing API (only an audit logs API for Enterprise)
  • Free paraphraser limited to 125 words and two modes
  • Prices vary by region
  • AI detection results are probabilistic