Earlier this week, OpenAI announced via blog post that it had launched two new AI models: GPT-5.4 mini and GPT-5.4 nano , with the former providing “significant improvements” over GPT-5.0 mini in various ways and bringing parts of the company’s latest model to more users. When OpenAI unveiled GPT-5.4 in early March, the company described the model as primarily aimed at more advanced tasks, such as programming and data analysis. With GPT-5.4 mini, users on the Free and Go tiers now also have access to a simpler version of that. GPT-5.4 mini offers improvements over GPT-5.0 mini in areas such as reasoning ability, multimodal understanding, and tool use. At the same time, it’s said to be more than twice as fast as its predecessor. In ChatGPT, Free and Go users can use the new GPT-5.4 mini model by selecting the “Thinking” mode. For all other users, GPT‑5.4 mini is a rate-limited fallback for the more powerful GPT‑5.4 Thinking.