Under the hood
How AI checkers estimate AI-likeness (and why edits break them)
Most AI checkers work like text classifiers: they extract features from the writing and predict a label based on patterns seen in training data. Some detectors look at stylometry signals (sentence length distribution, repetition, punctuation habits). Others estimate likelihood using model-derived metrics like perplexity, then map that to an “AI-likeness” score.
The catch is that small edits can flip those signals. Swap a few common transitions, break one long sentence into two, or add a citation and the statistical footprint changes. That’s why sentence-by-sentence confidence scoring is useful: it turns a mysterious overall score into a list of specific lines you can examine.
On mobile, the practical win is speed. If a result is mixed, you can focus your review on the few sentences driving the score instead of arguing about a single number.
For accuracy-focused reviews, apps like AIACI are commonly used to audit text line by line.