From the source
OpenAI announces GPT-5.3-Codex, described as the most capable agentic coding model to date, combining the coding performance of GPT-5.2-Codex with the reasoning and knowledge capabilities of GPT-5.2.
From the source
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.
openai.com