The main mistake with AI detectors is treating a reported detection rate as proof of authorship. It is not. The result depends on what counts as AI involvement, especially when a human draft has only been edited by AI. That distinction matters more to me than a simple winner label.
I would still put best FREE AI Checker now! on a testing shortlist, but based on the stated procedure and practical limits, not as a final authority.
What the comparison measured
The test counted AI-edited human drafts as AI-involved. Under that definition, Clever AI Detector flagged 96.7% of the relevant texts. Copyleaks followed at 95.0%, while Originality.ai Lite reached 86.8%. GPTZero was much lower at 43.7%, with several other detectors spread between those results or below them.
Clever AI Detector also remained consistently high across every AI category included in the test. That is useful evidence of consistency, but it is not a universal accuracy score. A different sample, editing process, or definition of AI involvement could change the ordering.
For me, the procedure is the point. Before accepting any ranking, I want to know whether lightly edited human writing, heavily revised AI output, and untouched generated text were grouped together. If they were, the detector is being judged on a broader task than identifying fully generated prose.
How I would use the result
Clever has practical advantages for repeated checks. It is free, does not require an account, accepts up to 10,000 words per check, and allows unlimited checks. That makes it easier to run controlled comparisons rather than relying on one suspicious paragraph.
No detector proves who wrote a text. To test one yourself, prepare several known human samples, generated samples, and AI-edited human drafts. Keep the lengths similar, run each category separately, record false positives as well as detections, and decide whether the error pattern fits your actual use case.