Free AI Detector — Detect ChatGPT, Claude & GPT-4
Paste any text and we'll score it on burstiness, vocabulary diversity, and perplexity, the same three signals Turnitin, GPTZero, and Originality.ai use.
Four signals every modern AI detector watches
Our scoring model ensembles the same statistical signatures used by Turnitin, GPTZero, and Originality.ai, and the score is calibrated against their public benchmarks.
Burstiness
Human writers mix short and long sentences. AI writers default to medium-length, even cadence.
Vocabulary
AI leans on a narrow set of "transition" and "academic" words. Humans pull from a wider range.
Perplexity
How predictable each next word is. AI text is highly predictable — almost compressible. Humans surprise.
Repetition
AI repeats structural patterns ("It is important to…", "Furthermore…"). Humans rarely do.
From AI draft to detector-proof in 90 seconds
Most students and writers run the same loop. Here's how to actually use this tool.
Detect
Paste your draft and check the AI score before you submit anywhere.
Re-detect
Paste the humanized version back. Confirm 80%+ before submitting.
Submit
Send to Turnitin, GPTZero, your editor, or Google with confidence.
How our detector compares
Same signals, same accuracy band — without the paywall, the sign-up, or the data retention policy.
| Feature | TextHumanizer | GPTZero | Originality.ai | Turnitin |
|---|---|---|---|---|
| Free, no sign-up | ✓ | Limited | Paid | Institution only |
| Burstiness + perplexity scoring | ✓ | ✓ | ✓ | ✓ |
| Per-detector breakdown | ✓ | — | Partial | — |
| Built-in humanizer | ✓ One-click | — | Add-on | — |
| Stores your text | Never | May log | Yes | Yes |
| API access | $0.005/check | $0.01+ | $0.014+ | Enterprise only |
Built for the three writers most at risk
Pre-screen before Turnitin
Run your draft through our detector before you submit. If it scores below 70%, route the flagged passages through the humanizer. Cheaper than an academic-integrity hearing.
Audit before you publish
Google's helpful-content systems penalize low-effort signals — and AI text patterns into low-effort. Detect first, humanize where needed, publish with confidence.
Verify freelance + team work
Suspect a contributor of using ChatGPT? Paste their work in. The breakdown shows exactly which sentences read AI-like — receipts, not vibes.
How our AI detector works
Modern AI detectors look at three statistical signatures simultaneously: burstiness (variation in sentence length), vocabulary diversity (lexical patterns vs. common AI defaults), and perplexity (how predictable each next word is). Human writing scores high on all three; AI writing scores low.
Our detector ensembles these signals and benchmarks against the same training corpora used by Turnitin, GPTZero, and Originality.ai. The score you see is calibrated against academic + commercial detection tools — if our detector flags it, theirs likely will too.
The big advantage: when our detector flags something, you can fix it in the next tab. The humanizer is tuned against the exact same signals — so a 38%-likely-AI score becomes a 91%-likely-human score in one click. No detector + paid-humanizer round-trip across three different vendors.
Detector vs. humanizer — when to use which
The detector tells you whether text reads AI-like. The humanizer fixes it. They're meant to be used together: detect → humanize → re-detect → submit.
If your goal is just to check (e.g. a freelancer's draft, a student paper, a competitor's blog post) — stay on this page and use the detector alone. If your goal is to publish or submit AI-assisted writing safely — use both, in that order.
Most users start with the detector to triage existing drafts, then route flagged passages through the humanizer. The full workflow takes about 90 seconds for a typical 800-word essay.
Frequently asked questions
Try the rest of the toolkit
Run all your text through TextHumanizer.
Humanize · detect · plagiarism scan · grammar check — all in one workspace. 100 free uses/month, no credit card.