OpenAI has released two AI “reasoning” models that it says are its most capable yet as well as an open-source AI agent that helps computer programmers code, as the company seeks to gain a lead over its rivals. The open-source coding agent, called Codex CLI, marks the first time since 2019 that OpenAI has introduced a significant open-source tool.

Following the recent launch of a new family of GPT-4.1 models, OpenAI released o3 and o4-mini on Wednesday, the latest addition to its existing line of reasoning models. The o3 model, previewed in December, is OpenAI's most advanced reasoning model to date, while o4-mini is a smaller, cheaper, and faster model.