GPTZero

GPTZero is an AI detection platform that uses a combination of perplexity and burstiness analysis — statistical measures of text predictability and variation — to assess the likelihood that a piece of writing was produced by an AI language model rather than a human author. The tool returns a probability score for the full document along with sentence-level highlighting that identifies specific passages most likely to be AI-generated. This granular breakdown is useful for reviewers who need to understand which sections of a document require closer scrutiny rather than simply receiving a binary pass or fail result. The free plan provides 10,000 words per month of basic AI scanning with three Advanced Scans included. GPTZero's primary user base consists of educators and academic institutions screening student submissions for AI-generated content, alongside publishers, HR teams, and content operations that verify the originality of written work before approval or publication. The Premium plan at $12.99 per month billed annually — or $23.99 month-to-month — covers 300,000 words per month with full Advanced AI Scan access, multilingual detection, and downloadable reports. See similar solutions. The Professional plan at $24.99 per month annually — $45.99 monthly — adds up to 500,000 words per month, batch scanning of up to 250 files simultaneously, page-by-page scanning for longer documents, overage capacity up to 10 million words, and enterprise-grade security with LMS integration for institutional deployment. GPTZero is among the earliest and most recognized AI detection tools and is specifically built for the academic and editorial use cases that drive most detection demand. The sentence-level highlighting makes it more actionable than tools that return only a document-level score. As with all AI detection platforms, accuracy is not absolute — false positives can occur with highly formal human writing, and false negatives are possible with heavily paraphrased AI content. GPTZero is most reliable when used as one signal in a broader content review process rather than as a standalone deterministic judgment tool. The free tier is genuinely useful for low-volume detection needs without requiring a credit card Read our guide.