ChatGPT detector that shows its work
Paste any text to check whether it was written by ChatGPT — GPT-4o, GPT-4.1 or GPT-5. You get an AI percentage and every sentence that reads like ChatGPT highlighted, so you can see the evidence instead of trusting a number.
AI detection returns a probability estimate — use it as a strong signal, not absolute proof. Your text is never stored.
How a ChatGPT detector works
ChatGPT writes by predicting the most likely next word, and it does so extremely well. That is also its weakness: the resulting text is more predictable, more evenly paced and more generic than writing produced by a person. A ChatGPT detector measures those properties — how predictable each word is (perplexity), how much sentence length varies (burstiness) and how often stock phrases and structures appear — and turns them into a probability.
Detect AI runs that analysis sentence by sentence. Instead of a single verdict, it highlights the specific sentences that drive the score. That matters because real text is rarely all-or-nothing: a student may write most of an essay and let ChatGPT finish a paragraph; a marketer may draft with GPT-4o and then rewrite half of it by hand.
The detector is not tied to one model version. GPT-4o, GPT-4.1, the o-series reasoning models and GPT-5 share the same underlying tendencies, and the same analysis catches them. Text from Gemini, Claude, Llama and DeepSeek is also detected — this page simply focuses on the tells that are most characteristic of ChatGPT.
Six signs a text was written by ChatGPT
The detector measures these statistically; you can also spot them by eye.
Rule-of-three lists
"Fast, reliable and affordable." ChatGPT groups qualities in threes far more often than people do.
Stock transitions
Additionally, moreover, furthermore, in conclusion, it is important to note — connectors that human writers use sparingly.
Even sentence length
Nearly every sentence lands between 15 and 25 words. People mix five-word sentences with forty-word ones.
Summaries that restate
Paragraphs that open with a topic sentence and close by repeating it, and essays that end with "In conclusion" followed by the introduction again.
Abstract, hedged vocabulary
Leverage, delve, landscape, robust, seamless, navigate, foster — abstractions in place of a specific example or number.
No personal detail
Nothing a person would have to have been there to know: no names, dates, mistakes, opinions or sensory detail.
A percentage and the sentences behind it
A ChatGPT score above 80% with most sentences highlighted means the text follows machine patterns throughout. A score between 30% and 70% with scattered highlights usually means a mixed origin — a human draft polished by ChatGPT, or a ChatGPT draft edited by a person. Both are common, and the highlights tell you which paragraphs to look at.
Because ChatGPT's newer models write more naturally than GPT-3.5 did, no detector should be treated as proof. Combine the score with context: does the writer's earlier work sound like this? Can they explain the argument? Is there any detail only they could know? Those questions settle more cases than any percentage.
GPT-3.5, GPT-4, GPT-4o, GPT-4.1, o-series and GPT-5
Each generation of ChatGPT has become harder to detect by eye. GPT-3.5 was repetitive and formulaic; GPT-4 and GPT-4o smoothed the surface and added more varied vocabulary; GPT-4.1 and GPT-5 follow instructions to "sound human" more faithfully. The statistical fingerprints — low perplexity and low burstiness — persist across all of them, which is what the detector relies on rather than on surface phrases alone.
The practical consequence is that longer samples matter more with newer models. Fifty words of GPT-5 output can look convincingly human; three hundred words rarely do. Paste full paragraphs, and if you are checking your own writing, run the highlighted sentences through the AI humanizer and check again.
When people reach for a ChatGPT checker
Essays and assignments
Teachers screen submissions; students confirm their own work will not be falsely flagged.
Cover letters and applications
Recruiters spot templated letters; applicants make theirs sound like a person.
Blog posts and guest articles
Editors check freelance copy; publishers keep their sites from reading like a content farm.
Reviews and messages
Moderators and support teams identify mass-generated reviews, comments and outreach.
Everything you need to check, fix and clean AI text
Detect AI is one of three free tools that work together. Check a text, rewrite it in a human voice, or remove the invisible characters AI tools leave behind — no account for any of them.
AI Detector
Paste any text and get an AI probability score with every suspicious sentence highlighted. Works for ChatGPT, GPT-4o, Gemini, Claude and more.
Open tool →✍️AI Humanizer
Rewrite AI-sounding text so it reads naturally. Choose a reading level, purpose and strength, then see the before-and-after AI score.
Open tool →🧹AI Watermark Remover
Find and delete zero-width characters, hidden Unicode tags and odd spaces that AI tools embed in copied text. Runs entirely in your browser.
Open tool →ChatGPT detector — frequently asked questions
Can it detect GPT-4o and GPT-5?
Yes. The detector measures statistical properties shared by every ChatGPT generation, not phrases specific to one version. Longer samples give more reliable results with the newest models.
Is this different from the main AI detector?
It is the same engine. This page explains the tells specific to ChatGPT and how to read the result for that case; the homepage covers all models.
Can ChatGPT text be made undetectable?
Heavy editing or humanizing lowers the score, sometimes into the human range. That is why we highlight sentences: edited text usually still contains a few that read as AI.
Does it detect ChatGPT in languages other than English?
Yes, across 40+ languages. English has the most training data and therefore the most reliable scores.
How many words do I need?
At least 10 to run a check, 50 or more for a confident result, and a full paragraph or two for the newest models.
Will it tell me which version of ChatGPT was used?
No. It estimates whether text is machine-generated; attributing a specific model version is not reliable with current methods, and we would rather not pretend otherwise.
Can a human-written text be flagged as ChatGPT?
Yes — formal, templated or second-language writing is predictable and can score high. Treat the result as a signal and look at the highlighted sentences before drawing a conclusion.
Is the ChatGPT detector free?
Completely. No account, no word cap, no paid tier.
Checked your text? Fix what was flagged
Run the highlighted sentences through the free AI humanizer, or remove hidden characters with the watermark remover before you submit.