OpenAI brings GPT-5.4 mini to ChatGPT, Codex, and the API

OpenAI said on March 17, 2026 that GPT-5.4 mini is now available in ChatGPT, Codex, and the API. In the X post, the company described the model as being optimized for coding, computer use, multimodal understanding, and subagents, and added that it is 2x faster than GPT-5 mini.

The wording matters because it frames GPT-5.4 mini as a deployment-oriented model rather than a pure benchmark update. By emphasizing speed alongside coding and computer-use tasks, OpenAI is signaling a model tier meant for interactive agent workflows, tool-calling loops, and production scenarios where latency and cost discipline matter almost as much as raw capability.

The inclusion of subagents is also notable. That term points to orchestration patterns where one model manages or delegates work across multiple smaller tasks, which fits how developers are increasingly building agent systems inside ChatGPT, Codex, and API-based products. OpenAI did not publish detailed benchmarks in the post itself, but the launch language suggests the company sees GPT-5.4 mini as a practical model for developers who need broad capability without always using the largest frontier tier.

Availability: ChatGPT, Codex, and the API

Positioning: optimized for coding, computer use, multimodal understanding, and subagents

Speed claim: 2x faster than GPT-5 mini

Source: @OpenAI on X.