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.

✓ 100% free ✓ No sign-up ✓ Text never stored ✓ Up to 2,000 words

0 words

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Highlight: reads human uncertain reads AI · hover any part for its own score

Thanks — noted. Reports like yours are how we improve the model.

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.

See the full accuracy report and limitations →

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.

All DetZero tools

Everything on the site, in one list. The detector pages run on our server — text is scored in memory and discarded. The writing, time and calculator tools run entirely in your browser: nothing is uploaded. The same tools are also browsable on the Free Tools hub.

Japanese tools （日本語ツール）

Japanese Tools Hub （日本語ツール）

文字数カウント, kaomoji, Japanese calculators, age & era tables, PDF merge — 27 tools in Japanese.

AI Detector

How it works

1. Our own trained model

2. Three signals, one score

3. Checked on our server only

How accurate is it?

Checking something specific?

Frequently asked questions

All DetZero tools

AI Detector pages

Text & Writing — counters & utilities

Text & Writing — fancy text & font generators

Text & Writing — symbols & kaomoji

Timers & Clocks

Dates

Calculators

Japanese tools （日本語ツール）