AI Detector
A free AI checker for text from ChatGPT, GPT-5, Claude, Gemini and DeepSeek. Paste any text and DetZero scores how likely it is to be AI-generated — with the exact sentences that drive the score highlighted.
How it works
1. Our own trained model
DetZero's classifier was trained on tens of thousands of paired texts — modern human writing and AI versions of the same content — so it learns the real difference, not just keywords.
2. Three signals, one score
The neural classifier is combined with a text-predictability measure and writing-rhythm features (sentence variation, stock phrases) into a single AI-probability score.
3. Checked on our server only
Every check runs on DetZero's own server. No outside AI service sees your text, and nothing you paste is stored or logged.
How accurate is it?
We publish our real validation numbers instead of marketing claims. On our current benchmark — human texts with natural formatting, matched to the AI texts for length — DetZero catches 82% of AI text at a false-flag rate of about 1% on human text. On topics unlike the benchmark, expect closer to 58%. One honest gap: documents that mix human-written and AI-written passages are hard for us to catch. Real-world text is messier than any test set, so treat any single result as a strong signal, never as proof of who wrote something.
Checking something specific?
ChatGPT Detector
Checking an essay, assignment or email you suspect came from ChatGPT? Our dedicated ChatGPT Detector page explains how GPT-5-era writing is caught — and where the limits are.
AI Checker Free
Need a general-purpose check with no account and no cost? The AI Checker Free page covers text from every major model — ChatGPT, Claude, Gemini and DeepSeek — for teachers, students and editors.
Accuracy & limits
Before you act on any score, read the accuracy page: the full validation results, how the model was built, and the honest limitations of AI detection.
Frequently asked questions
Is DetZero free?
Yes. DetZero is completely free and needs no sign-up. You can check up to 2,000 words per check.
Do you store the text I paste?
No. Your text is scored in memory on our server and immediately discarded. It is never written to disk, never logged, and never used to train our models. See the privacy page.
What AI models can DetZero detect?
DetZero is trained on modern human writing and on current AI models, including the ChatGPT and GPT-5 family, Claude, Gemini and DeepSeek. Heavy human editing and humanizer tools can change the score.
How does the detector work?
DetZero runs its own trained neural classifier, combined with a text-predictability signal and writing-rhythm features. Every check runs on our own server — no third-party AI API sees your text.
How accurate is it?
In our latest validation — on a benchmark of naturally formatted human and AI texts matched for length — the current model caught 82% of AI text at a false-flag rate of about 1% on human text. No AI detector is perfect or proof of authorship — see our accuracy page for the full numbers and limits.
Can I use the result as proof someone used AI?
Please don't. Detectors can be wrong in both directions — including on writers who write in a second language. Use the score as one signal among several, not as sole evidence.
More from DetZero
Free Online Tools
96 free browser-based tools — word counters, timers, calculators, text generators, symbols and Japanese tools — on our main site, detzero.com.
Japanese Tools
Character counters, kaomoji, Japanese calculators, age & era tables and PDF tools, all in Japanese.