OpenAI has launched two new lightweight models, GPT-5.4 mini and GPT-5.4 nano, described as its most capable small models yet. The models are accessible to free and Go-tier ChatGPT users through a new “Thinking” option rather than a direct model selector. In testing, the Thinking models produced more detailed, multi‑step answers than the standard ChatGPT response, offering clearer reasoning for travel planning and online‑income strategies. While slightly less deep than the full‑size GPT-5.4 Thinking model available to Plus users, the mini and nano versions are faster and provide a notable upgrade for free users. Read more →