GPTZero is an AI-powered text analysis tool designed to detect content generated by large language models. It analyzes writing characteristics including perplexity and burstiness to determine whether text was human-written or AI-generated. In 2026, GPTZero remains the go-to solution for educators and content publishers needing AI detection. Key features include sentence-level analysis, multiple detection models, browser extensions, and API access. The free tier offers 5,000 words per month with basic detection. Premium plans provide unlimited access with advanced AI models for professional use. GPTZero achieves 91% accuracy on pure AI-generated content with the lowest false positive rate among free tools. Best use cases include academic integrity verification, content publishing, recruitment, and freelance work verification.