AI Checker Free
One free checker for AI writing from any major model — ChatGPT, GPT-5, Claude, Gemini or DeepSeek. Paste the text, get an AI-probability score with the driving sentences highlighted. No sign-up, no card, nothing stored.
Who uses a free AI checker?
Teachers
Homework and take-home essays now sit next to a chatbot that writes fluently on any topic. A quick check helps you decide which submissions deserve a conversation — and which are just a student having a good writing day.
Students
Check your own draft before you hand it in. If your genuine writing scores high — stiff phrasing, formulaic structure — you will know exactly which passages to loosen up before a teacher's checker sees them.
Editors & content teams
Freelance submissions and guest posts increasingly arrive with an AI first draft underneath. Screening copy before it reaches your site protects both your search rankings and your readers' trust.
Every major model, one checker
You rarely know which chatbot produced a piece of text, so a checker trained on a single model's habits is a checker with a blind spot. DetZero's model is trained on modern human writing set against output from the current generation of systems — ChatGPT and GPT-5, Claude, Gemini and DeepSeek — and it is retrained as those models change, because their writing styles change with them.
On our current benchmark — human texts with natural formatting, matched to the AI texts for length — the checker catches 82% of AI text at a false-flag rate of about 1% on human text. One case stays genuinely hard: documents that mix human-written and AI-written passages. A score is evidence to weigh, not a verdict to act on alone. The accuracy page shows the full results, including the cases where detection is weakest.
Free means free
Plenty of “free” checkers mean a free first paragraph, then a paywall. This one doesn't: no account, no email address, no card, no daily limit theatre — paste up to 2,000 words and get the full score and the full highlighting. However you phrase the search — “AI detector free” or “free AI detector” — the page you land on is the whole checker. We can offer that because the checker runs on our own model, on our own server. Your text is not sent to ChatGPT or any other company's API, is never written to disk, and is never used to train anything. When the result appears, the text is already gone.
Specifically checking something you believe came from ChatGPT? Our ChatGPT Detector page runs the same model with guidance written for that case — including why GPT-5 output slips past older detectors.
How it works
1. Paste the text
Anything from 40 to 2,000 words: an essay, a blog draft, a product description, an application letter. Longer samples give steadier scores than short ones.
2. Three signals score it
A trained neural classifier, a text-predictability measure and writing-rhythm features are combined into one AI-probability score — on our server, in seconds.
3. See the evidence
The text returns highlighted sentence by sentence, so a score is never just a number: you can see precisely which parts read as machine-generated and judge for yourself.
Frequently asked questions
Is this AI checker really free? What is the catch?
It is really free, and there is no catch to unlock: no account, no card, no trial that expires. DetZero runs its own model on its own server, so a check costs us almost nothing — we would rather earn trust with a free tool than gate a score behind a paywall.
Which AI models does this checker cover?
The model is trained on writing from the current generation of AI systems — ChatGPT and the GPT-5 family, Claude, Gemini and DeepSeek — alongside modern human writing, so it is not tied to a single chatbot's style.
How much text can I check at once?
Between 40 and 2,000 words per check. Below 40 words there is not enough signal for a meaningful score; for longer documents, split them into chunks and check the parts that matter most.
Is the text I check used to train your model, or shared with anyone?
Neither. Your text is scored in memory on DetZero's own server and immediately discarded. It is never stored, never logged, never used for training, and never sent to a third-party AI service. See the privacy page.
How accurate is this free checker?
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. That is strong, but not certainty — our accuracy page publishes the full results and limitations.
Can I check text in languages other than English?
The model is trained on English writing, so English results are the reliable ones. Other languages may return a score, but treat it as experimental.
Is an “AI detector free” the same thing as a “free AI detector”?
Yes — the two phrases are the same search in a different word order, and both describe this page: an AI detector that is free to use, with no sign-up and no card. Whichever way you typed it, the checker above is the full tool, not a demo with the real thing behind a paywall.