OpenAI is slowly inviting selected users to test a whole new set of reasoning models named o3 and o3 mini, successors to the o1 and o1-mini models that just entered full release earlier this month.

For the finale of its 12 Days of OpenAI livestream event, CEO Sam Altman revealed its next foundation model, and successor to the recently announced o1 family of reasoning AIs, dubbed o3 and 03-mini.