Introducing GPT-5.3-Codex

Launched GPT-5.3-Codex, the most capable agentic coding model yet. This model is the first that combines Codex + GPT-5 training stacks, bringing together best-in-class code generation, reasoning, and general-purpose intelligence in one unified model. It's approximately 25% faster, sets new highs on key benchmarks, and marks a step-change from code generation to a general-purpose coding agent you can actively steer while it works.