Codex was OpenAI's biggest and main first-party product, and the first product OpenAI developed with its product, model harness, and research functions together under one organization.

“I would say, like, Codex was really, like, our biggest and main one, and, um, it was the first time we developed a product where the product, the model harness, and the, the research was all kind of under one house and under one roof, and it really gave us a lot of flexibility to, um, go about building things.”