Paste something you wrote by yourself, then something a tool helped draft. The page counts eight things in both, the same way, and lays the numbers side by side. There is no detector in it. The baseline is you.
The method, and every mistake I made building it, is in the field guide.
Nothing you paste leaves this page. The counting happens in your browser, and closing the tab erases it.
The eight counts
The shape of the sentences
Your own handThe draft
Three questions
The sentences behind the counts
Every one of these is a real sentence that real writers use. Read them, and compare the rate to your own hand.
Measure, quote, and then decide for yourself. Nothing in this should ever block you from sending.