AI detection works by analyzing statistical properties of text that correlate with machine-generated output: low perplexity (the degree to which each word is highly predictable given prior words), low burstiness (human writing alternates between simple and complex sentences; AI writing stays uniform), and characteristic n-gram frequencies that reflect large language model training distributions.
This checker scores submitted text for the probability it was generated by an AI model. Paste any text, a student submission, freelance article, product description, or blog post, and receive a detection score with highlighted passages that most resemble AI-generated writing. Use it for editorial review before publishing AI-assisted content, or to verify that humanized output is sufficiently differentiated before submitting to platforms that screen for AI content.
How it works
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Paste your text
Paste any text you want to check. No word limit.
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Run the analysis
Four linguistic signals are measured: perplexity, burstiness, vocabulary, and phrase patterns.
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See your scores
Get estimated scores for GPTZero, Turnitin, Originality.ai, and Writer.com instantly.
What gets measured
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4 detector estimates
GPTZero, Turnitin, Originality.ai, and Writer.com scores all from one paste.
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Perplexity analysis
Measures how unpredictable your word choices are. Higher is more human.
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Burstiness scoring
Checks sentence length variation. Low burstiness is the top detection signal.
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Vocabulary pattern check
Identifies AI words like delve, crucial, pivotal, leverage, and 27 others.
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Instant results
No word limits, no signup, no API calls. Analysis runs server-side in under a second.
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Free forever
No account required. Check as many texts as you need.
Frequently asked questions
How do I check if my text will be flagged by GPTZero or Turnitin?
Paste your text above and click Check AI Detection. The tool analyzes four linguistic signals that GPTZero, Turnitin, Originality.ai, and Writer.com all measure: perplexity (word predictability), burstiness (sentence length variation), AI vocabulary density, and pattern score. Results show estimated detection probability for each platform with explanations.
What percentage score is safe for Turnitin AI detection?
Turnitin flags content above roughly 20% AI probability for further review. Most institutions consider 0-10% as clearly human, 10-20% as borderline, and above 20% as likely AI-generated. These thresholds vary by institution. GPTZero uses similar ranges. For academic submission, aim for under 10% on our checker, then verify on the actual platform.
What is perplexity in AI detection?
Perplexity measures how unpredictable your word choices are to a language model. High perplexity means surprising, unexpected vocabulary, a signal of human writing. Low perplexity means the text follows highly predictable patterns, a signal of AI generation. Human writers use varied, idiosyncratic word choices. AI optimizes for coherence, which produces low perplexity.
What is burstiness and why do AI detectors measure it?
Burstiness measures variation in sentence length. Human writing naturally mixes very short sentences with longer, complex ones. Short. Then a sentence that develops an idea across multiple clauses before arriving at a conclusion. AI writing tends to produce sentences of similar length throughout. Low burstiness is one of the strongest signals that text was AI-generated.
Can AI detectors tell the difference between ChatGPT and Claude output?
Advanced detectors like Originality.ai can identify which model likely generated content based on characteristic patterns. GPT-4 uses em dashes heavily and follows specific structural templates. Claude tends toward longer sentences and particular vocabulary. However, detector accuracy for model attribution is lower than simple AI vs human classification.
How accurate are AI detection tools in 2026?
Leading detectors achieve 85-95% accuracy on unedited AI content. False positive rates (flagging human writing as AI) remain a concern, academic and technical writing with precise, repetitive vocabulary can score as AI-generated. GPTZero has lower false positive rates than Originality.ai. This tool's estimates are based on linguistic analysis, not the actual detector models.
Does Google use AI detection to penalize content?
Google does not publish an AI detection score or threshold. Its helpful content system evaluates expertise, originality, and value to readers, signals that correlate with genuine human authorship but are distinct from AI detection. Low-quality AI content that adds no value gets demoted. High-quality content passes regardless of origin.
Why does my human-written text score as AI-generated?
False positives happen when human writing resembles AI patterns: formal academic style, technical documentation, repetitive vocabulary in specialized fields, and content that follows standard templates (how-to guides, listicles) all trigger false positives. If you are a human writer scoring high, add more sentence variation, personal opinions, specific examples, and less formal vocabulary.
What AI detection score should I aim for when submitting to clients or academia?
For academic submission: under 10% on Turnitin and GPTZero combined. For content marketing: under 20% on Originality.ai (their standard client threshold). For general publishing: no universal standard exists. If your content scores above 30% on our checker, use Vortenza Humanizer to reduce AI patterns before submission.
How is this tool different from GPTZero, Turnitin, and Originality.ai?
GPTZero, Turnitin, and Originality.ai use proprietary models trained on millions of AI-generated samples. This tool provides free linguistic analysis, measuring the same underlying signals (perplexity, burstiness, vocabulary) as a fast pre-check. Think of it as a pre-flight check before testing on the actual detector. For verified results, always test on the actual platform.
