GPT-5.3-Codex and Opus 4.6 launched within 10 minutes of each other yesterday

OpenAI Introduces GPT-5.3-Codex: Enhanced Coding and Agentic Capabilities

GPT-5.3-Codex is about more than just writing code

Anthropic and OpenAI Launch New AI Models Amid Escalating Rivalry and Super Bowl Ad Battle

The rivaling AI companies pushed GPT-5.3-Codex and Claude Opus 4.6, and had back-to-back appearances on a tech and business podcast.

OpenAI's GPT-5.3: Codex Capabilities and Speculation on Non-Codex Versions