OpenAI announces o3 and o4-mini reasoning models for ChatGPT (updated)

UPDATE: Apr. 16, 2025, 2:18 p.m. EDT Now that the OpenAI livestream has ended, this article has been updated with the latest information about the o3 and o4-mini launch.

OpenAI's o3 and o4-mini models for ChatGPT have arrived.

As expected, during a livestream event today, the ChatGPT maker released the newest versions of its reasoning models. OpenAI launched o1, its first reasoning or chain-of-thought model, last summer and skipped over o2 to announce its progress on o3 in late December.