A detector built over winter break
GPTZero launched in January 2023, built by Princeton undergraduates Edward Tian, who remains co-founder and chief executive, and Alex Cui, co-founder and chief technology officer. The tool classifies text as human-written, AI-generated, or a mix of both, aimed first at teachers trying to catch AI-written homework. Early demand outran the servers: the tool logged 30,000 uses in its first week and needed emergency hosting help to stay up. [5][6]
The company grew from an education tool into a broader authenticity product. GPTZero now says it has 17 million users, including a million educators and more than 3,500 colleges, plus over 100 organizations across hiring, publishing, and legal work. Its detector, built from a proprietary model with seven components, checks writing against outputs from Claude, ChatGPT, GPT-5, and Gemini. [1]
Auditing the research record
GPTZero's tools are not only aimed at student essays. On January 21, 2026, the company ran its detector against every one of the 4,841 papers NeurIPS accepted for its 2025 conference and reported 100 confirmed hallucinations spread across 53 papers, mostly citations to work that does not exist. Every one of those papers had already cleared peer review, which is the detail that made the finding notable: the fabrications survived a review process built to catch factual problems. [4]
Atlas interpretation: The finding doubles as an advertisement for GPTZero's own product, since it is both the auditor and a company that sells the auditing tool. That does not make the underlying count of fabricated citations wrong, but it is worth keeping in mind when reading GPTZero's own reports on AI-generated content, including this one. [4]
Acquired by Superhuman
On June 23, 2026, Superhuman, the productivity company that also owns Grammarly, announced it was acquiring GPTZero. Financial terms were not disclosed. Coverage at the time put GPTZero at roughly 19 million registered users and about $30 million in annual recurring revenue. Superhuman already had its own AI-detection feature; GPTZero's team described the deal as combining two detection efforts rather than one company absorbing a competitor out of existence. [3][2]
GPTZero's own announcement told users the acquisition changes nothing day to day: the detection, hallucination-checking, and writing-replay features continue under the GPTZero name. The company's stated rationale leaned on a Superhuman-commissioned study with Graphite estimating that half of internet content is now AI-generated, the scale problem GPTZero says the combined authenticity layer is meant to address. [2]
Sources
- AI Detector - Free AI Checker for ChatGPT, GPT-5 & Gemini
GPTZero · Aug 20, 2026
- GPTZero plans to join Superhuman
GPTZero · Jun 23, 2026
- Superhuman acquires AI detection startup GPTZero
TechCrunch · Jun 23, 2026
- GPTZero finds 100 new hallucinations in NeurIPS 2025 accepted papers
GPTZero · Jan 21, 2026
- Team
GPTZero · Sep 9, 2026
- A college student made an app that can tell if AI wrote an essay
NPR · Jan 9, 2023