GPTZero

Properties

category: detector
maturity: established
approach: AI-text detection using statistical signals (perplexity and burstiness) plus trained classifiers to label text as human, AI, or mixed across major models (ChatGPT, Claude, Gemini, Llama).
access: freemium
owns: Detects AI-generated text and checks writing quality, aimed at educators and editors; offers writing-origin reports and learning-management-system integrations.
distinctFrom: Unlike a watermark-remover (which defeats detection) or a provenance standard (which cryptographically signs origin), GPTZero is a classifier that scores whether existing text is AI-written.
source: GPTZero (gptzero.me)
notes: Acquired by Superhuman (formerly Grammarly) on June 23, 2026; GPTZero's AI and hallucination detectors are being integrated into Superhuman Go as an authenticity layer. Co-founders Edward Tian and Alex Cui joined Superhuman. At the acquisition Tian told Business Insider GPTZero had more than 19 million registered users and $30 million in annual recurring revenue (per TechCrunch). As of 2026-10-25 gptzero.me announces a new model ('Introducing GPTZero-4o, the world's most accurate AI detector') and claims 99.9% accuracy and 20M+ users; all accuracy and user figures are self-reported, not independently verified.

category: detector
maturity: established
approach: AI-text detection using statistical signals (perplexity and burstiness) plus trained classifiers to label text as human, AI, or mixed across major models (ChatGPT, Claude, Gemini, Llama).
access: freemium
owns: Detects AI-generated text and checks writing quality, aimed at educators and editors; offers writing-origin reports and learning-management-system integrations.
distinctFrom: Unlike a watermark-remover (which defeats detection) or a provenance standard (which cryptographically signs origin), GPTZero is a classifier that scores whether existing text is AI-written.
source: GPTZero (gptzero.me)
notes: Acquired by Superhuman (formerly Grammarly) on June 23, 2026; GPTZero's AI and hallucination detectors are being integrated into Superhuman Go as an authenticity layer. Co-founders Edward Tian and Alex Cui joined Superhuman. At the acquisition Tian told Business Insider GPTZero had more than 19 million registered users and $30 million in annual recurring revenue (per TechCrunch). As of 2026-10-25 gptzero.me announces a new model ('Introducing GPTZero-4o, the world's most accurate AI detector') and claims 99.9% accuracy and 20M+ users; all accuracy and user figures are self-reported, not independently verified.