Free AI Detector
Check if Text Was Written by
ChatGPT, Claude, or Gemini
Paste up to 500 words. Instant verdict with a precise AI probability score. Free with a signup.
How it Works
How the AI Detector Works
Three steps from unknown text to a clear AI verdict
Paste & hit detect
Drop any text — email, essay, article, or message — into the scanner and click Detect. Up to 500 words per scan.
What We Detect
What Our Detector Catches
ChatGPT, Claude, Gemini & other LLMs
Covers GPT-4 and GPT-5 output, Claude Sonnet and Opus, Gemini Pro, Llama, and Mistral — not just one provider.
Paraphrased AI text
Flags AI output that has been run through paraphrasers like QuillBot or spun by a second model to dodge basic detectors.
Edited AI drafts
Picks up mostly-AI text with light human edits — the most common case for assignments and ghostwritten blog posts.
Mixed human + AI writing
Sentence-level probability surfaces the AI portions even when human writing is blended in around them.
Comparisons
How It Compares: GPTZero, Turnitin, Originality.ai
Most detectors specialize in one slice of the problem. Here is how HumanWriteup's detector lines up against the three names you have probably already tried.
vs GPTZero
GPTZero pioneered perplexity-based scoring and still works well on raw ChatGPT output, but it can be fooled by light paraphrasing or by newer models with smoother token distributions. HumanWriteup's detector layers structural fingerprinting on top of perplexity, so it keeps a precise score even after a paraphrase pass — and it covers Claude and Gemini, not just GPT.
vs Turnitin
Turnitin's AI indicator is tuned for the academic essay format and is locked behind institutional accounts — you cannot just paste an arbitrary email or blog draft into it. Our detector is free, instant, and works on any text up to 500 words per scan while reading the same kind of stylistic patterns Turnitin flags.
vs Originality.ai
Originality.ai is strong on long-form web content and bills itself as the SEO publisher's detector, but you pay per scan. HumanWriteup is free for one-off checks and uses the same paraphrase-aware scoring approach, so editors and bloggers can spot-check drafts without burning credits.
Testimonials
Trusted by Students, Marketers, and Researchers
Join the students, marketers, and researchers who use HumanWriteup every day.
“I was skeptical, but it genuinely rewrites things to sound like me. Saved my thesis deadline.”
“We use it for first drafts daily. Cuts our editing time in half and the output is clean.”
“The formal mode is incredible. The output finally reads like something I'd write myself.”
FAQ
AI Detector FAQ
Failed the check? Make it pass.
Run it through HumanWriteup and clear every major AI detector — GPTZero, Turnitin, Originality.ai, Copyleaks.
Humanize your text