OpenAI has released GPT-5.4 Mini and Nano, its most capable small models yet, specifically designed for the emerging subagent era.
GPT-5.4 Mini significantly improves over GPT-5 Mini across coding, reasoning, multimodal understanding, and tool use, while running more than 2x faster. It approaches the performance of the larger GPT-5.4 on evaluations including SWE-Bench Pro and OSWorld-Verified.
GPT-5.4 Nano is the smallest and cheapest variant, optimized for tasks where speed and cost matter most — classification, data extraction, ranking, and coding subagents that handle simpler supporting tasks.
The architecture is designed for agentic composition: a larger model like GPT-5.4 handles planning, coordination, and final judgment, while delegating to Mini or Nano subagents that execute narrower subtasks quickly at scale.
GPT-5.4 Mini is available in the API, Codex, and ChatGPT, supporting text and image inputs, tool use, function calling, web search, file search, computer use, and skills. ChatGPT's free tier now gets GPT-5.4 Mini with improved coding capabilities.
GPT-5.4 Nano is currently API-only and not yet accessible in ChatGPT or Codex.
The release signals OpenAI's recognition that the future of AI isn't just bigger models — it's efficient, specialized models that can work together in orchestrated workflows.