The mistake I would correct first is treating a confident AI label as proof of authorship. In my checks, ZeroGPT and NoteGPT assigned the Lewis Carroll excerpt their strongest AI scores, above the generated writing. ZeroGPT called it 99.3% AI. That makes me look for known-human controls before giving much weight to successful detections.
The reverse errors mattered too. QuillBot accepted all four generated passages as human. Scribbr missed the generated essay, as did SciSpace and Proofademic’s public demo. Surfer missed the generated essay and story. I cannot explain those failures from screenshots. Scribbr also displayed QuillBot branding, so I would not automatically treat agreement between them as independent confirmation.
I used six unchanged English passages on October 2–3, 2026: generated writing in essay, memo, paraphrase, and fictional personal-story formats, a Carroll excerpt, and an AI-edited version of that excerpt. Some passages were related. This was a limited comparison, not evidence about everyone’s writing, and I did not evaluate paid workflows or multilingual coverage.
I also separated a completed result from an interface that merely looked finished. GPTZero retained an old score after I replaced the input; that was not another detection. Sapling checked only part of the essay, although its complete story and human checks were correct. GPTZero, Grammarly, and Quetext correctly flagged the generated material they processed, but account barriers left me without human controls for them. Their successful detections do not establish false-positive performance.
For a repeat of this small guest-access exercise, I would start with the Clever AI Detector tool. It completed the set without payment or registration, caught the generated passages, and accepted Carroll. I could not verify its advertised unlimited use or maximum length. Its sentence colors and explanations sometimes disagreed with the headline, and it accepted the lightly edited passage as human.
Pangram also accepted that edited passage, while correctly classifying its completed generated and original-human checks. Its credits ran out, with usage depending on length. Originality.ai and AI or Not likewise got their completed generated and human checks right, with narrower coverage. Originality.ai’s confidence applied to a verdict under the selected allowance, not a measured proportion of generated words. I would not compare confidence, probability, and estimated AI share as interchangeable values.
Access-only observations tell me nothing about accuracy. Decopy requested login; Smodin hid its headline values. AI Detector Pro and Winston AI required registration, while Turnitin needed institutional access. I stopped at Copyleaks’ applicable-use terms, not a failed scan. Hive’s text routes required an extension or API; ContentDetector.AI redirected to a Moxby extension listing. I installed neither extension nor Humanly’s app, and could not verify their detection or free allowances.
To test this yourself, use writing whose origin you can document, including your own drafts, generated samples, and separately labeled edited mixtures. Submit identical copies, confirm that each result is new and covers the whole passage, and save the output. Compare errors by category rather than averaging unlike scores. I would use those records to judge usefulness, not to turn a detector label into an accusation.