GPTZero AI

GPTZero highlights the exact sentences in a document that look machine-written, not just whether the whole thing trips the detector. Paste in text and you get a percentage confidence score plus sentence-by-sentence highlights showing which bits score highest for AI authorship. It recognises output from ChatGPT, GPT-4, and Claude, and the entire tool is free with no account required for quick checks. The catch is reliability: accuracy drops on shorter samples, false positives happen regularly, and it misses anything a human has manually edited or paraphrased, which is exactly what careful students and content mills do. It's for teachers spot-checking assignments, publishers verifying submissions, or HR teams running a first-pass filter on applications. If you need to catch polished, human-edited AI work, look elsewhere.