What the AI Detector does
AI Detector asks an AI model to assess whether a piece of text reads as human-written or AI-generated. You paste text or upload a PDF, and you get a probability score, a verdict, written reasoning, and two lists of signals: patterns typical of AI writing, such as uniform sentence structure and stock phrases, and signs of human writing, such as varied sentence length, personal detail, and informal phrasing.
How to read the result
The score is an estimate produced by a language model judging the style of the writing; it is not a forensic test and it cannot see how the text was actually produced. Treat the reasoning and the lists of signals as a prompt to look more closely, not as a verdict. You need at least 250 characters for a meaningful result, and about the first 25,000 characters are analyzed.
Why detectors make mistakes
All AI detectors, including this one, produce false positives and false negatives. Human writing that is formal, formulaic, or very polished can be flagged as AI, and writing by non-native English speakers is flagged more often. Lightly edited AI text can pass as human. Short texts are especially unreliable.
For that reason, a detector score should never be the sole basis for accusing someone of using AI, grading someone down, or rejecting work. If authorship matters, talk to the writer, look at drafts and version history, and use several kinds of evidence.
Privacy and limits
Your text is sent through our server to an AI model; PDF Studio does not keep a copy, but the AI service processes it. Each tool allows 10 requests per minute per visitor. Scanned PDFs contain no text, so run OCR PDF first.