Most AI detectors charge per scan or require a monthly subscription. GPTZero offers limited free checks, Originality.ai costs $14.95/month, and Turnitin requires an institutional license. This one is free for the first 1,500 words of any document, with no sign-up and no credit card, and a full document of up to 30,000 words costs €4.99 once - not per month. Upload a PDF or DOCX or paste your text to get an analysis across 16 AI writing indicators, and, unlike every tool listed above, the measured rate at which that verdict is wrong about human-written academic work is shown next to it.
Free AI Detector - No Sign Up Required
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Free to 1,500 WordsNo Sign-Up RequiredNo Credit CardUnlimited Re-ChecksError Rate PublishedInstant Results
Why Choose Our Free AI Detector?
Free to 1,500 Words
Any document gets a real score on its first 1,500 words, and the result tells you exactly how much went unchecked. A full document is €4.99 once - no subscription.
No Registration
No account creation, no email verification, no personal data collection. Just upload and check.
Unlimited Re-Checks
Run the free check as many times as you like. There are no daily limits, no monthly quotas, and no per-scan charges.
We Publish Our Error Rate
Every verdict states how often that same verdict is given to verified human-written academic text. No competitor publishes this, because publishing it means having measured it.
How Our Free AI Detector Works
- Upload your document in PDF or DOCX format, or paste your text directly into the tool.
- Our detector analyzes 16 statistical indicators across five families: vocabulary diversity (MTLD, hapax, Yule's K), sentence rhythm (length uniformity, length variation, burstiness, opening diversity), phrase fingerprints (60+ AI-favored phrases and transition word frequency), document structure (paragraph uniformity, passive voice, sentence-to-sentence flow), and statistical fingerprints (Zipf exponent, character entropy, punctuation diversity, word length variation).
- Each factor is scored from 0 to 100 and weighted to produce an overall AI probability score.
- Review the detailed per-factor breakdown to understand exactly which patterns were detected.
- Revise flagged sections and re-check as many times as you need - unlimited, free.
Free vs. Paid AI Detectors
- GPTZero: Free tier limited to 5,000 characters. Premium starts at $10/month.
- Originality.ai: $14.95/month for 200,000 words. No free tier.
- Turnitin: Requires institutional license ($3+ per student per year).
- Copyleaks: Free tier limited. Premium from $9.99/month.
- ThesisDraft AI Detector: First 1,500 words free. No sign-up. Whole document for EUR 4.99.
Frequently Asked Questions
The first 1,500 words of any document are free, with no sign-up, no credit card and no cap on how many times you run it. Checking a full document of up to 30,000 words is €4.99 as a single payment, which includes 14 days of unlimited re-checks. There is no subscription.
The tools that are free at any length are funded by a subscription somewhere else, or by selling something. A single €4.99 payment for the one thesis you actually need to check is cheaper than every monthly plan in this category, and it means we do not need your ongoing custom to stay in business.
The free tier reads the first 1,500 words and the result tells you exactly how many words went unchecked. Accuracy varies by language and document length, and where we have not measured a case we say so - short German text, for example, never receives a high-probability verdict because our measurements do not support one.
We use statistical analysis comparable to paid detectors, and we publish the measured rate at which each verdict is wrong about verified human-written academic text. No competitor publishes that figure. Paid tools may offer extras we do not, such as API access or batch processing.
We keep the text that was actually analysed - on the free tier that is the first 1,500 words, not your whole document - so that we can measure and improve the detector. It is stored without your name, email, or any payment identifier, because we never ask for them. We do not add your work to any plagiarism database, and we never will.
Yes. Essays, theses, dissertations, research papers, homework, articles - any text document in PDF or DOCX format, or pasted directly.
Related AI Check Tools
Check your whole thesis
Check the whole document instead of the first 1,500 words, with our measured error rate beside the verdict and a report you can download. One payment of €4.99, no subscription, no account.
See what the full check costs