GPT-5-Codex Is Now the Default in Codex — OpenAI's Purpose-Built Agentic Coding Model Explained
OpenAI’s Codex just got a major upgrade at the model level. As of April 4, GPT-5-Codex is the default model across Codex CLI, the Codex IDE extension, and Codex cloud environments. This isn’t GPT-5 — it’s a distinct variant, purpose-built for agentic coding workflows. What Is GPT-5-Codex? GPT-5-Codex is a GPT-5 variant optimized specifically for the demands of autonomous coding agents. Where GPT-5 is a general-purpose model, GPT-5-Codex is trained and tuned for: ...