Criterion Grammarly Originality.ai
CategoryAI Writing & Content CreationAI Detection & Plagiarism Checking
In one sentenceA writing assistant that checks grammar, clarity, and tone as you type across websites and apps.An AI content detector and plagiarism checker aimed at publishers, agencies, writers and educators.
Problem it solvesCatching grammar, spelling, and clarity issues everywhere you write, not just in one editor.Helps content teams and educators check whether text may be AI-generated or plagiarised before publishing or grading it.
Free planYesYes
Developer APINoYes — docs
Open sourceNoNo
PlatformsWeb, Browser extension, Windows, macOS, iOS, AndroidWeb, Chrome extension, Google Docs, Firefox, API
Pricing (summary)Free tier covers core checks; Premium adds advanced suggestions. Verify current plans on Grammarly's site.
Checked 2026-10-05		A free Basic tier offers limited AI-detection scans per day without a subscription; paid Pro and Enterprise plans use monthly credits and add plagiarism and other checks, the Chrome extension, team features and (on Enterprise) API access, and one-time credit purchases are also available. The site says there is no free trial. Verify current plans on Originality.ai's pricing page.
Checked 2026-10-13
Strengths
  • Works nearly everywhere you type
  • Explanations teach as they correct
  • Combines AI detection, plagiarism, fact-checking and readability tools in one product
  • Team management, scan history and an API suit agencies and publishers
  • The vendor openly advises that an AI score should be one signal among several, with a human in the loop
Limitations
  • Suggestions are not always contextually right
  • Full features need a paid plan
  • Detection results are probabilistic and can produce false positives; Originality.ai itself says a score shouldn't be used alone for academic integrity discipline, so it should never be the sole basis for academic or disciplinary decisions
  • The free Basic tier is limited to AI detection with a small daily scan and word allowance
  • Text entered into the free tool may be used for training unless you have an account and opt out