Estimates how machine-written a passage reads, then shows you exactly which sentences are doing it and why. Nothing you paste leaves this page.
Paste the version you rewrote in your own words. You get both scores and how much of the text you actually changed. The tool never rewrites anything for you.
Read the number as a mirror, not a verdict. This checks writing style: sentence rhythm, vocabulary, connectives, punctuation habits, how much of a person is in the text. ZeroGPT, GPTZero and Turnitin mostly measure something else, how predictable each word is to a language model, so their numbers will differ from this one and from each other.
Every detector, this one included, flags formal, polished or non-native English as machine-written some of the time, and misses machine text that has been lightly edited. No score proves anything either way. What does hold up is being able to explain every sentence you hand in, out loud, in your own words.