GPT-5.4 Pro is OpenAI’s most capable model, extending GPT-5.4’s unified architecture with stronger reasoning for complex, high-stakes tasks. It includes a 1M+ token context window (922K input, 128K output) and supports both text and image inputs. Tuned for step-by-step reasoning, instruction following, and high accuracy, GPT-5.4 Pro stands out in agentic coding, long-context workflows, and multi-step problem solving.