The latest models for ChatGPT users and developers using OpenAI's API are designed to be workhorses, built for tasks like vibe coding, where big, powerful AI models are expensive overkill. GPT-5.4 mini and nano, which OpenAI released Tuesday, are the smallest and fastest versions of GPT-5.4, which debuted earlier this month.
These new models are part of an effort by OpenAI to lean into coding as it battles with rival Anthropic for the AI software engineering market. OpenAI's latest models for its Codex coding software have directly challenged Anthropic's Claude Code, which went viral at the end of 2025 for its ability to create apps from scratch.
Disclosure: Ziff Davis, CNET's parent company, in 2025 filed a lawsuit against OpenAI, alleging it infringed Ziff Davis copyrights in training and operating its AI systems.
OpenAI says GPT-5.4 mini is more than twice as fast as its predecessor, GPT-5 mini, at tasks like coding, reasoning and tool use. On some benchmarks, it's close to the capabilities of the standard GPT-5.4 model.
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The company suggested GPT-5.4 mini is best for things like editing and debugging code. It could be used as a subagent in Codex, with a larger model like GPT-5.4 delegating certain tasks to the faster, cheaper model.
GPT-5.4 nano is even smaller, and OpenAI suggested it for grunt work like classifying and extracting data.
GPT-5.4 mini will be available for developers through the API and through Codex and ChatGPT. ChatGPT Free and Go users can access it through the "Thinking" feature. Others will find it as the fallback model when they hit the rate limit for GPT-5.4 Thinking. GPT-5.4 nano is only available in the API.
