GPT-5.3-Codex System Card
OpenAI Blog ● Covered by 2 sources
GPT-5.3-Codex combines the coding abilities of GPT-5.2-Codex with the reasoning and professional knowledge from GPT-5.2 into a single model. The system card does not specify performance benchmarks, release date, or concrete capability metrics. This combination of coding and reasoning capabilities enables more complex software development tasks previously requiring multiple models.
Why it matters
GPT‑5.3-Codex is the most capable agentic coding model to date, combining the frontier coding performance of GPT‑5.2-Codex with the reasoning and professional knowledge capabilities of GPT‑5.2.