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

• GPT-5.3-Codex can now operate a computer as well as write code
• It's also quicker, uses fewer tokens and can be reasoned with mid-flow
• Codex 5.3 was even used to build itself and the team was "blown away"

OpenAI has launched a new and upgraded version of Codex which the company says is about far more than just performance updates.

With GPT-5.3-Codex, the platfrom goes from being a code writer and reviewer to a computer-using agent capable of handling many tasks developers are likely to do on their machines. Of course, stronger reasoning and knowledge also form part of the package, too.

For example, GPT-5.3-Codex is 25% faster than version 5.2 and uses fewer tokens, supporting longer and more complex tasks.