GPTOne

GPTOne is a free AI content detector that instantly spots text written by ChatGPT, Claude, Gemini, and other major AI models. Paste your text and get fast, reliable results in seconds. It's more than a detector, though GPTOne bundles a grammar checker and a humanizer (Soon), and a word counter into one clean workspace, so you can check and polish your writing without juggling five different tools. 16+ languages supported, including Italian, Spanish, French, and Chinese.