ChatGPT Detector
Paste text you suspect came from ChatGPT — an essay, an assignment, a suspiciously polished email — and DetZero scores how likely ChatGPT wrote it, with the sentences behind the score highlighted.
Why GPT-5 writing is harder to catch
Most AI detectors were built in the GPT-3.5 era, when machine writing had obvious tells: repetitive phrasing, lopsided sentence lengths, a limited vocabulary. GPT-5 writes nothing like that. Its answers are evenly paced, well organised and, on factual topics, read like a competent encyclopedia entry — exactly the style older classifiers learned to associate with careful human writing.
We know, because it happened to us. An earlier DetZero model scored a fresh, unedited ChatGPT answer about the history of India as almost certainly human — and when we later rebuilt our test benchmark honestly, we found that model had partly learned a formatting shortcut in its training data rather than a writing signal. The current model — the one running on this page — is an ensemble validated on that corrected benchmark: it catches 81% of OpenAI-generated texts at a false-flag rate of about 1%, and it catches that same history-of-India answer decisively. That gap is the whole reason this page exists separately: a “ChatGPT detector” that has not been rebuilt for GPT-5 is mostly decoration. Our accuracy page tells the full story, including the numbers we got wrong before.
What people check here
Essays & assignments
A term paper that arrived fully formed, in a voice unlike the student's classroom writing. Paste the introduction and a middle section — 40 words minimum, more is steadier.
Emails & cover letters
Job applications and workplace emails are now routinely drafted by ChatGPT. A check won't tell you who held the pen, but a very high score on a “personal” statement is worth a second look.
Posts, reviews & comments
Forum answers and product reviews generated in bulk have a sameness to them. Checking two or three samples from the same account is more informative than checking one.
How the check works
Paste at least 40 words (up to 2,000 at a time) and press Check text. DetZero combines three signals: its own neural classifier, retrained for the GPT-5 generation of models; a text-predictability measure; and writing-rhythm features such as sentence variation and stock phrasing. The result is a single AI-probability score, and the text comes back with each part highlighted — green where it reads human, red where it reads machine-generated — so you can see which sentences are driving the verdict instead of trusting a bare number.
Scores fall into three bands: under 20% reads as human, 20–60% is a mixed picture (often a person writing over an AI draft, or the reverse), and 60% and above reads as likely AI. Everything runs on DetZero's own server — your text is never sent to OpenAI or any other third party, and it is discarded the moment the score is computed. And if you found this page by searching for a “chat GPT detector” with a space, you are in the right place — the spaced spelling lands on the same checker.
Checking text from other models too?
ChatGPT is the most common source, but not the only one. If the text might have come from Claude, Gemini or DeepSeek — or you simply want the general-purpose version of this tool — use our AI Checker Free page; it runs the same model with guidance for mixed sources. And before you act on any result, read the accuracy page for the full validation numbers and the cases where detection fails.
Frequently asked questions
Can this detector catch GPT-5, or only older ChatGPT versions?
Both. The current DetZero model is an ensemble built for current generators, including the GPT-5 family: on our latest benchmark — naturally formatted texts, matched for length — it caught 81% of OpenAI-generated texts at a false-flag rate of about 1% on human text. Earlier detectors, including our own previous model, missed most GPT-5 text.
Is this ChatGPT detector free to use?
Yes. It is completely free, needs no sign-up or account, and checks up to 2,000 words at a time.
Can't I just look for a ChatGPT watermark instead?
Not reliably. Text copied out of ChatGPT carries no visible watermark you can inspect, and any statistical watermark is destroyed by editing or retyping. Detection has to be based on the writing itself, which is what this page does.
A student insists they wrote the essay themselves. Is a high score proof they used ChatGPT?
No. Our verdicts are set so that only about 1% of human texts score as likely AI, but no threshold turns a score into proof. Treat a high score as a reason to talk and to look at drafts, notes and writing history — never as sole proof.
What if the text was edited after ChatGPT wrote it?
Editing pulls the score down. Lightly edited ChatGPT text often lands in the Mixed band, and heavily rewritten or “humanized” text is the hardest case for every detector, ours included.
Do you keep the text I paste into the checker?
No. The text is scored in memory on our own server and immediately discarded. It is never written to disk, never logged, and never used to train our models. See the privacy page.
I searched for a “chat GPT detector” with a space — is that a different tool?
No. “Chat GPT detector” is just the spaced spelling of the same search, and this page is that tool: paste text from ChatGPT — the app or the web version, free or paid — and it scores how likely ChatGPT wrote it.