OpenAI launches GPT‑5.3-Codex as AI race heats up after Anthropic’s Claude Opus 4.6 — all you need to know

Sam Altman-led OpenAI launched GPT-5.3-Codex, which is a fast, agentic model that it believes goes beyond coding and can handle research and workflows. Rival Anthropic’s Claude Opus 4.6 focuses on long-running tasks and deep reasoning.