• 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.

GPT-5.3-Codex is a huge upgrade over 5.2

As well as scoring well across the SWE-Bench Pro and Terminal-Bench benchmarks, GPT-5.3-Codex also set strong scores across OSWorld (computer-use tasks) and GDPval (knowledge work across 44 occupations).

Some of Codex 5.3’s use cases include building complex games and web apps from scratch, self-iterating over millions of tokens with little to no additional human input. But when it does come to human collaboration, users can question and redirect Codex mid-flow instead of waiting for it to finish.

As for another major first, GPT-5.3-Codex has become the first OpenAI model to help build itself. “The Codex team used early versions to debug its own training, manage its own deployment, and diagnose test results and evaluations,” the announcement reads. “Our team was blown away by how much Codex was able to accelerate its own development.”

All paid ChatGPT plans can now get access to GPT-5.3-Codex on the app, CLI, IDE extension and web. And it comes just days after the ChatGPT-maker launched a dedicated Codex app on macOS.

With this tool, “Codex is moving beyond writing code to using it as a tool to operate a computer and complete work end to end,” OpenAI wrote.

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With several years’ experience freelancing in tech and automotive circles, Craig’s specific interests lie in technology that is designed to better our lives, including AI and ML, productivity aids, and smart fitness. He is also passionate about cars and the decarbonisation of personal transportation. As an avid bargain-hunter, you can be sure that any deal Craig finds is top value!