AI Detector Reviews
Who each detector is for, what independent research found, and where each falls short. No affiliate links, no paid placements.
| Detector | Best for | Free option | Our take |
|---|---|---|---|
| GPTZero | Teachers and students who want a widely known detector with sentence highlighting | Free plan with a monthly word allowance (10,000 words a month as of late 2025) | A solid, accessible detector for screening, especially on unedited text. Not a tool to base a penalty on by itself. |
| Turnitin AI Writing Detection | Schools and universities that already license Turnitin | No individual plan; available through institutions | Convenient for institutions, with sensible guardrails. Its process-based Clarity tool is the more meaningful development. |
| Originality.ai | Publishers, content marketers, and agencies checking web content | A few free daily scans (3 scans up to 2,000 words without an account, per its site) | A good fit for publishers and agencies who want detection plus content quality checks in one place. |
| Copyleaks | Schools and businesses that need multilingual detection and LMS integration | Free scans without logging in (up to 25,000 characters, per its site), more with a free account | A practical choice for multilingual settings and institutions that want detection inside their LMS. |
| Pangram | Anyone who prioritizes a low false positive rate, including researchers and publishers | Free checks available; see its site for current limits | Currently the strongest detector in independent testing we’ve reviewed. Still a screening tool, not a verdict. |
| Grammarly AI Detector and Authorship | Writers who already use Grammarly and want to show how they wrote something | AI detector and Authorship are both available on the free plan, per Grammarly | One of the best mainstream ways for writers to show their process. A natural alternative or complement to Prove Human. |
| QuillBot AI Detector | Quick, free checks by students and writers | Free for all users; premium adds batch uploads | Fine for a quick look. Use a more rigorously tested detector when the stakes are higher. |
| ZeroGPT | Casual, free checks | Free web checks | We would not rely on it for any decision that affects someone. |
Read a detector review
GPTZero
One of the first and best-known AI detectors, launched in January 2023 by Princeton student Edward Tian. It is popular in education and also offers authorship-tracking tools that show editing history.
Read the review →TurnitinTurnitin AI Writing Detection
Built into the plagiarism-checking software many schools already use. Instructors see an AI writing percentage alongside the similarity report. In 2025 Turnitin also launched Turnitin Clarity, a writing space that shows teachers how a submission was written.
Read the review →Originality.aiOriginality.ai
Aimed at people who publish content professionally. It combines AI detection with plagiarism checking, fact checking, and readability tools, plus a browser extension that replays how a Google Doc was written.
Read the review →CopyleaksCopyleaks
A long-standing plagiarism-detection company that added AI detection in early 2023. It emphasizes multilingual support and integrations with learning management systems.
Read the review →Pangram LabsPangram
A newer detector that has posted the strongest results in several independent evaluations, including very low false positive rates and resistance to humanizer tools.
Read the review →GrammarlyGrammarly AI Detector and Authorship
Grammarly offers a free AI detector, but its more important tool is Authorship, which tracks whether text was typed, pasted, or generated with AI help, and produces a shareable report and replay.
Read the review →QuillBotQuillBot AI Detector
QuillBot is best known for its paraphrasing tool and also offers a free AI detector. Premium users can upload up to 20 files at a time.
Read the review →ZeroGPTZeroGPT
A widely used free online detector. It gained attention in 2023 when screenshots showed it, along with other detectors, labeling the U.S. Constitution as AI-generated.
Read the review →