toolai detect
words0
lang50+
Free AI Detector — Paste Text or Upload a Document
AI content detector · ai2human
human <25%mixed 25–40%ai >40%
Free AI checkerNo login required to start
AI Detector — See Exactly Which Sentences Are AI
Our AI detector tells you how likely a piece of writing was generated by AI — and unlike a tool that returns a flat score, it shows you why. This free AI checker analyzes every sentence for linguistic patterns common to ChatGPT, GPT-5, Claude, Gemini, and other large language models, then highlights the exact passages that triggered each flag. Paste text or upload a PDF — no login required to start.
50K+
Documents scanned
<3s
Average scan time
50+
Languages supported
Free
No login required
how it works
Three signals. One careful read.
Instead of a single mysterious number, we run independent detection layers in parallel and combine them into one weighted score you can actually interrogate.
01perplexity
How surprising is each word?
We score predictability with a language model. Machine writing is unusually easy for a machine to predict — that's the tell.
02burstiness
Does the rhythm breathe?
Human writing has bursts: a tight sentence, then a sprawling one. Model writing settles into a metronome. We measure the variance.
03context
Read with you, not for you.
Every sentence is shown with its score and reasoning. You make the judgment. We never auto-fail, auto-report, or grade for you.
why ai2human
Transparency a flat percentage can’t give you.
Most tools return a single number. We show you the evidence — sentence by sentence — so you can apply judgment, not just trust a score.
Sentence-level evidence
See precisely which lines moved the score and why — the detail a flat percentage never shows.
Results in under 3 seconds
Four detection layers run in parallel. No waiting, no queue — results arrive instantly.
50+ languages
Perplexity and burstiness signals are language-agnostic. Reliable AI detection in 50+ languages.
Signal-level transparency
Go beyond a score. See exactly which patterns triggered each flag — sentence by sentence.
PDF & Word upload
Upload full essays in PDF or DOCX. Text is extracted automatically — no copy-pasting.
No institutional account
Students, educators, and freelancers get full access without an enterprise agreement.
accuracy & limitations
How accurate is AI detection, really?
No AI detector is 100% accurate — any tool that claims otherwise should be treated with caution. Detection is probabilistic: it estimates likelihood from linguistic patterns. Short passages, heavily edited text, or non-native writing can all affect results.
97.3% accuracy on clear-cut text
In our internal benchmark of 10,000 labeled documents, the tool achieved 97.3% agreement on clearly AI-generated or clearly human-written text. Mixed and heavily paraphrased samples are the hardest case for every detector.
How to read a high score
A result above 40% is a reason to look closer — read the flagged sentences, consider the context, and ask for additional evidence before drawing conclusions about authorship.
False positives can happen
Formulaic or highly structured human writing — legal, technical, or non-native — can score higher than expected. Sentence-level evidence helps you spot where the signal is strong and where it's noise.
Never the sole verdict
No AI detector should be the only basis for an academic or employment decision. Use results alongside other evidence — earlier drafts, a conversation, a writer's stylistic history.
what our users say
Real results. Verified by teachers.
“Finally a detector that doesn’t flag my students’ naturally varied writing as AI. The false positive rate is much lower than GPTZero.”
Priya R.
High school English teacher
who uses it
From students to publishers.
Students
Self-check your essay before submitting so honest, naturally varied writing isn't mistaken for AI.
Learn more →
Educators
Verify submissions and start a conversation about responsible AI use — without a costly institutional license.
Content & SEO teams
QC AI-assisted drafts and protect search performance and brand voice before publishing.
Learn more →
Recruiters & Publishers
Spot-check resumes, cover letters, and freelancer submissions for authenticity.
faqs
Common questions.
About our free AI checker, how it works, and how to read results.
AI-powered tools for your writing needs
One platform. Five powerful tools. Everything you need to humanize, detect, and perfect your writing.
AI Humanizer
Transform AI-generated text into undetectable human writing that bypasses every major detector.
99% on Turnitin
Pass Rate
5M+ and growing
Words Processed
40+ supported
Languages
Try Humanizer Free
Free · No signup required
Detected high AI signal in your draft? Our AI Humanizer can rewrite flagged passages in a more natural, varied voice.
Compare AI2Human with alternatives: vs QuillBot, vs Undetectable.ai, vs HIX Bypass.
For students: AI tools for students covers responsible AI use and academic integrity.
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