Writing · 5 tools · updated Oct 15, 2026
Check whether text or an image was AI-generated
Turnitin leads with an evidence score of 12/100, ahead of QuillBot (11) and Copyleaks (10). 3 of 5 can be used free. Best for institution-wide academic integrity: Turnitin.
Ranked by evidence — GitHub stars, Hacker News mentions, release activity and how much you can use for free. Recomputed nightly. How the score works.
+ Already deployed at most universities, so AI scores appear inside the workflow instructors use.
− No individual access, and its AI indicator has led to disputed accusations against students.
+ The paraphraser's mode slider (fluency, formal, simple, creative) is the fastest way to rework a clumsy paragraph.
− Paraphrased text sometimes changes meaning, and its humanizer and detector are unreliable against serious detection tools.
+ Supports 30+ languages and integrates with Canvas, Moodle and Blackboard.
− Credit-based pricing is confusing, and false positives on edited human text are common.
+ Highlights which sentences look AI-generated and offers a Google Docs writing replay as supporting evidence.
− Like all detectors it produces false positives, particularly on non-native English writers.
+ Combines AI detection, plagiarism, fact-check and readability scans with team seats and a full-site scan.
− Known for aggressive detection that flags human writing, with no free tier.
Head to head: Turnitin vs QuillBot Turnitin vs Copyleaks QuillBot vs Copyleaks
Missing a tool? It gets added when it shows up in the release feed with real traction, not by request.