OpenAI unveils GPT-5.3-Codex, which can tackle more advanced and complex coding tasks

• GPT-5.3-Codex can now run a computer as well as write code
• It’s also faster, uses fewer tokens, and can be reasoned at mid-rate
• Codex 5.3 was even used to build itself and the team was “blown away”

OpenAI has launched a new, improved version of Codex that the company says goes far beyond simple performance updates.

With GPT-5.3-Codex, the platform moves from being a code writer and reviewer to an agent using a computer capable of handling many of the tasks that developers are likely to perform on their machines. Of course, stronger reasoning and knowledge are also part of the package.