GPTBot is OpenAI's web crawler. It fetches publicly available web content that can be used to train and improve OpenAI's models, and OpenAI also operates related agents such as OAI-SearchBot and ChatGPT-User for search and live browsing. Site owners can allow or disallow it in robots.txt.
For brands, the key fact is that GPTBot, like most AI crawlers, does not execute JavaScript. If your pages render their content only after JavaScript runs in the browser, GPTBot may see an empty shell, which is one of the most common reasons a site is invisible to AI. Serving server-rendered HTML and allowing the bot in robots.txt are the two prerequisites.