ChatGPT Text Detector

Paste any text to check if it was written by ChatGPT, GPT-4o, GPT-5, or any OpenAI model. Free, instant, no login required.

GPT-4o & GPT-5 Free Forever 75–90% Accuracy No Login

AI Text Detector

Paste any text — instant results, no login required

Free Forever 🔒 Private
0 words — 30 minimum for reliable results
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Analyzing…

Narrative Academic
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Signal Breakdown tap to expand

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Accuracy note: Browser-based detectors achieve ~70–80% accuracy. Use as a screening tool, not sole evidence of AI use. How it works →

What Makes ChatGPT Writing Detectable

ChatGPT produces four consistent patterns that persist across GPT-4o, GPT-5, and even o3 — despite OpenAI's efforts to reduce them.

Vocabulary Spike

Words like "delve", "meticulous", "tapestry", "pivotal", and "nuanced" spiked 3–28× in published writing after ChatGPT launched in November 2022 (Kobak et al., Science Advances 2025). GPT-4o and GPT-5 still produce them.

Transition Addiction

"Furthermore", "Moreover", "Additionally", "In conclusion" — ChatGPT uses these at a rate 4–6× higher than human writers. They appear even when the logical connection doesn't require them.

Metronome Paragraphs

Human paragraphs vary wildly in length. ChatGPT produces paragraphs of near-identical word counts — usually 55–75 words each, separated by perfect spacing. The burstiness coefficient is a dead giveaway.

Hedging Cluster

"It's worth noting that", "It is important to consider", "One might argue" — these hedging phrases cluster in ChatGPT text because the model was trained to be careful. Humans hedge too, but not in this specific pattern.

ChatGPT Versions This Covers

Detection works across the entire GPT family. Older models score higher because they were less trained to avoid vocabulary markers.

GPT-3.5 Turbo (~89% detection) GPT-4 (~82% detection) GPT-4o (~72% detection) GPT-4o mini (~75% detection) GPT-5 (~51–65% detection) o1 / o3 / o4-mini (~60% detection)
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Why does GPT-5 score lower? GPT-5 was specifically trained to vary vocabulary and sentence structure. It's better at avoiding vocabulary markers — but structural patterns like burstiness and closing rituals persist.

Real ChatGPT Text — Annotated

🤖 ChatGPT — Score: ~87%
"In today's rapidly evolving landscape, it is crucial to note that artificial intelligence marks a pivotal moment in human history. Furthermore, the intricate tapestry of technological considerations demands meticulous attention. It is worth noting that this development presents both opportunities and challenges that underscore the need for thoughtful engagement."

Flagged: "pivotal moment", "intricate tapestry", "meticulous", "underscore" (T1 vocab) + 2 transitions + 1 hedging cluster

Accuracy & Limitations

Browser-based detectors without LLM access achieve approximately 75–90% accuracy on unedited ChatGPT text. Here's what affects the score:

Unedited ChatGPT (GPT-3.5, GPT-4) 85–90%
GPT-4o / GPT-5 (less vocabulary markers) 65–75%
Human-edited ChatGPT output 40–60%
Heavily humanized with Undetectable AI 25–45%

ChatGPT Detector FAQ

Yes. GPT-4o and GPT-5 still produce vocabulary patterns from Kobak 2025 research. We also check structural signals like burstiness and closing rituals that newer models haven't eliminated.
75–90% on unedited ChatGPT essays. The vocabulary density and transition signals are especially strong in academic-style writing where ChatGPT defaults to formal patterns.
Yes — GPT-3.5 and GPT-4 score the highest (85–90%) because they were less trained to vary vocabulary. They produce the clearest fingerprints.
Yes, completely free. All detection runs as JavaScript in your browser — no server, no API, no login, no word limits.