OpenAI launched GPT-5.3-Codex as Anthropic released Claude Opus 4.6 in a simultaneous drop that kicks off the AI coding wars, ...

The new model is built to accelerate the capabilities of Codex, the agentic coding tool OpenAI launched earlier this week.

Dan tested Codex 5.3 on Proof, a macOS markdown editor that he's been vibe coding that tracks the origin of every piece of text—whether it was written by a human or generated by AI—and lets users ...