GPTZero

GPTZero runs what it describes as the world's leading AI-text identification platform, distinguishing human-written from machine-generated content. The company was founded in January 2023 by Edward Tian, then an undergraduate at Princeton University, and grew out of a senior thesis written over a winter break. It raised $13.5m in a Series A round.

The core product detects text produced by ChatGPT, GPT-4, Gemini, Llama, Claude and other large language models. It is complemented by a plagiarism checker, writing-feedback tools and a source-verification tool, which together form a broader suite aimed at information quality. The platform reports more than 10m users, among them 380,000 educators.

The company's stated purpose is to preserve what is genuinely human in an age of artificial intelligence and to restore quality and transparency to information on the internet. Its work spans natural-language processing, large language model analysis, plagiarism detection and source verification, and its customers are drawn from education, publishing and media, and internet content more broadly.