Claude Opus 4.6 vs GPT‑5.3-Codex,Two Powerful AI Models Launch on the Same Day

Claude Opus 4.6 and GPT‑5.3-Codex both came out in February 2026. It’s unusual for two big AI models to launch at the same time. Both are still in beta and are getting a lot of attention from companies and developers.

Claude Opus 4.6

Claude Opus 4.6 is made to handle long texts and complicated tasks. It can read and understand large documents or datasets without getting confused. This makes it useful for businesses, research projects, or any work that needs careful thinking over long text. Its strength is keeping information clear and connected, even when working with lots of text. People testing it say it works well when you need to understand big amounts of information in one go.

GPT‑5.3-Codex

GPT‑5.3-Codex is mainly for coding and automated workflows. It helps developers write code, fix errors, and handle multi-step programming tasks faster. This model is good for software development and automation. Testers have noticed it works smoothly even with complex code.

Both models came out at the same time, but they do different things. Claude Opus 4.6 is better for tasks with long documents or big datasets. GPT‑5.3-Codex is better for coding and developer tasks. Which one you should use depends on the type of work you need it for.