GPT-5.3-Codex is the newest and most capable version of OpenAI’s Codex, designed to handle advanced coding and broader professional workflows on a computer.
It builds on GPT-5.2-Codex with stronger coding, reasoning, and knowledge work capabilities, running about 25% faster and excelling at long-running tasks involving research, tool use, and complex execution.
The model achieves state-of-the-art benchmarks, produces functional software and websites, and supports debugging, deployment, tests, documentation, and more. Users can interact with it in real time as it works, steering progress. GPT-5.3-Codex is available in the Codex app, CLI, IDE extensions, and web for paid ChatGPT plans.
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