Free · Unlimited · Client-side

Is your text
AI-generated?

Paste any text and instantly see the AI score. Eight pattern checks run in your browser — no server, no login, no limits. See exactly which patterns a detector would flag.

8 pattern checks Zero data sent Works offline
0 words · free · unlimited

False positives

Falsely accused
of using AI?

AI detectors make mistakes — serious ones. A 2025 Yale case became a flashpoint when students faced academic discipline based solely on detector output. None were found responsible.

Research shows 5–20% false positive rates. Non-native speakers are hit hardest — formal academic writing in a second language shares structural patterns with AI output. This tool shows you exactly which patterns triggered the flag so you can fix them.

5–20%
False positive rate
Documented in peer-reviewed research
ESL
Most at risk
Second-language writers flagged disproportionately
Yale 2025 precedent
Students faced discipline based solely on AI detector output. No findings against any student. Detector alone is not proof.

8 pattern checks

What the detector
actually measures.

HIGH
Sentence variance
AI produces uniform sentence lengths (CV < 25%). Humans mix short punchy sentences with longer complex ones.
HIGH
AI vocabulary
Words like "furthermore," "delve," "robust," "seamless," "leverage" are drastically overrepresented in LLM output.
HIGH
Transition density
"However," "therefore," "consequently" appearing more than once per 50 words signals a model following an outline.
MEDIUM
Passive voice
AI favors passive constructions at rates higher than most human writers. 40%+ passive sentences is notable.
MEDIUM
No short sentences
Humans write "That was it." or "She left." AI defaults to complete multi-clause constructions every time.
MEDIUM
Em dash overuse
GPT-4 and Claude reach for em dashes as a stylistic default. 3+ in a short text is reliable signal.
MEDIUM
Parallel lists
Numbered or bulleted lists with grammatically parallel items are an AI organizational fingerprint.
LOW
Missing contractions
Humans use contractions constantly. AI defaults to formal full forms unless explicitly instructed otherwise.

$0 forever

Why is this
completely free?

The detection logic runs as JavaScript in your browser. When you click "Check for AI," no data is sent anywhere. No server processing, no API call, no database. The marginal cost of one more user running one more check is exactly $0.00.

Other tools that charge for AI detection are either using server-side models (which have real costs) or charging because they can. We keep the detector free because it serves a different purpose: it shows you the problem. If you want the problem fixed — the patterns actually removed — that requires an LLM rewrite, which is what the paid humanizer does.

Want to understand how detectors like GPTZero and Turnitin score your text? The Refrazr blog covers the math and practical strategies in detail — including a 100-essay test of GPTZero accuracy.

$0
per check
∞
unlimited
0 B
data sent

FAQ

Common questions.

How accurate is this AI detector?
The detector runs the same pattern analysis used by commercial tools like GPTZero and Sapling. It checks eight structural signals that LLMs consistently produce: low sentence length variance, AI vocabulary, heavy transition phrase usage, passive voice, absence of short sentences, em dash overuse, parallel list structures, and missing contractions. For typical AI-generated text, it catches 80–90% of cases. The analysis runs instantly in your browser — no server model involved.
Can AI detectors give false positives?
Yes. False positive rates of 5–20% are well-documented in academic research. A 2025 Yale case drew national attention after a professor accused students based solely on detector output — none were found responsible. Non-native English speakers are disproportionately flagged because formal academic writing from second-language speakers shares structural patterns with AI output. If your genuine writing is flagged, this tool shows exactly which patterns triggered the result.
What AI models can this detect?
The detector is model-agnostic. It looks for structural patterns common to all large language models — ChatGPT, Claude, Gemini, Llama, Mistral, and others. These models share training objectives and produce similar fingerprints: even sentence lengths, formulaic transitions, hedging vocabulary, parallel clauses. The specific model matters less than the patterns it leaves behind.
Is this detector free? Are there limits?
Completely free with no limits. The detection runs 100% client-side in your browser — no server calls, no API keys, no usage tracking. We can offer this because it costs us literally nothing to run. The only paid features are on the humanizer side, where we use an LLM to rewrite your text.
Does the detector store or log my text?
No. The text never leaves your browser. The analysis is pure JavaScript running locally. You can verify this by checking your browser's network tab: zero outbound requests when you click Check for AI.
My text scored high but I wrote it myself. What should I do?
Check which patterns triggered the score. If you see no contractions — add a few (it's, I've, don't). Low sentence variance — break up or combine sentences for rhythm variation. Heavy transitions — replace some however/therefore/furthermore with simpler connectives or nothing. These are the exact changes that make human writing look less like AI to automated tools.

Score too high?
We can fix that.

Refrazr rewrites at the structural level — eliminating the exact patterns this detector flagged. Deep structural rewriting, not synonym swap. Free tier available.

Try Refrazr free →