OpenAI releases GPT-5.4 mini and nano, its ‘most capable small models yet’ OpenAI continues to ship new models with the release of GPT-5.4 mini and nano, its “most capable small models yet.” ChatGPT users can start using GPT-5.4 mini today. https://9to5mac.com/2026/03/17/openai-releases-gpt-5-4-mi… https://9to5mac.com/2026/03/17/openai-releases-gpt-5-4-mi…