The free AI detector that makes sure the GPT is gone.

GPTGone is a completely free AI text scanner. Paste or upload some text and it estimates whether it was written by a person, by an AI model such as ChatGPT or Claude, or by a mix of both. It also highlights the sentences that look most machine-written and explains why.

Yes. Every feature is free for everyone, with no account, no trial and no paywall. Scan as many texts as you like, up to 1,000,000 characters each. Because the detector runs in your browser instead of on a server, there's nothing to meter and nothing to sign up for.

GPTGone runs two models in your browser. The main one is a compact neural network (a transformer) that we fine-tuned on more than 110,000 labelled human and AI texts. It reads your text in overlapping windows of about 120 words and scores how machine-like each one is. The second is a statistical model over 39 writing signals, such as how much sentence lengths vary, word choice, contractions, hedging and punctuation. GPTGone combines both into a calibrated score for the whole text and for every sentence, and shows you the signals behind it.

On more than 25,000 held-out test documents from 11 sources, GPTGone caught 89.6% of AI-written texts and flagged 2.2% of human ones; only 0.5% of human texts were called fully AI. Our previous rule-based detector caught 59% while flagging 27% of human writing. Harder cases score lower: brand-new models it never trained on, AI text run through paraphrasing tools, and AI drafts a person has edited. Every number, including the weak spots, is in our accuracy report. It works best on 150+ words of prose. Treat any result as one piece of evidence, never as proof.

Fairer than most, but not perfect. A 2023 Stanford study found that popular detectors flagged 52% to 76% of essays written by non-native English speakers for the TOEFL as AI-generated. On the same essays, GPTGone flags 11%, and none of the 88 essays by US eighth-graders from the study. That is a big improvement, but it is still not zero, which is one more reason never to treat a result as proof on its own.

Yes. The analysis runs entirely in your browser, so the text you paste or upload is never sent to us or anyone else. Your first scan downloads the detection model from this site (about 20 MB, once); after that it is cached on your device. The site's security policy blocks the page from sending data to any other server. There are no accounts and no scan history.

GPTGone learned from writing by more than 40 models: OpenAI's GPT-3.5 to GPT-5, Anthropic's Claude 3 to Claude 5.5, Google's Gemini 3, Meta's Llama, plus DeepSeek, Qwen, Mistral, Cohere, GLM and others. We also test it on models it never saw in training, because new ones appear all the time. It doesn't try to name the exact model, only whether the writing reads as machine-generated.

English. The models were trained on English, so results for other languages aren't reliable, and GPTGone tells you when a text doesn't look like English.

Sometimes, like every detector. Text that a person heavily rewrites by hand is the hardest case. GPTGone was trained on AI paraphrases and casual-sounding AI writing, and it catches common tricks such as invisible characters and look-alike letters from other alphabets. When it finds them, it says so in the result.

Please don't rely on it alone. Use a high AI score as a reason to look closer: talk to the writer, ask about their process and compare with work you know is theirs. The sentence highlights are there to make that conversation easier.

PDFs, Word documents (.docx, or .doc from older versions of Word) and plain text files (.txt and .md). The file is opened right in your browser, so it never leaves your device. GPTGone reads the main text and leaves out headers, footers, page numbers, footnotes and comments. PDFs don't store paragraphs, so GPTGone rebuilds them from the page layout; it's worth a glance at the text before you scan. Scanned PDFs are pictures of pages with no text inside, so they can't be checked. Each scan checks up to 1,000,000 characters (about 150,000 words), so a longer file is trimmed to its first 1,000,000. Very long texts take a while: the full 1,000,000 characters can take a few minutes on a computer and longer on a phone, and you can switch to a quick scan while it runs.