GPTZero
The most recognized AI content detector, born in an American university
Overview
GPTZero is one of the first mainstream AI content detectors, launched in 2022 by a Princeton student. It analyzes the "perplexity" and "burstiness" of text to estimate the likelihood it was generated by an LLM (ChatGPT, GPT-4, Claude, Gemini…). The interface is simple: paste text, get a probability score, and sentence-by-sentence highlighting.
It comes in a limited free version (10,000 words/month, 5 advanced scans) and paid plans starting around $10/month with annual billing. The API is available on higher plans, allowing detection integration into editorial or HR workflows.
Our verdict
GPTZero is a good entry point for editorial or HR teams wanting a quick first check. But watch out: its false positive rate remains non-negligible (human text flagged as AI), and authors who "humanize" their content fool it easily. Use as an indicator, never as proof. Avoid for consequential decisions (exams, layoffs).