Sep 16, 2025 11:12:00

Introducing 'GPT-5-Codex,' further improving GPT-5's coding capabilities and supporting work in editors and terminals

OpenAI released ' GPT-5-Codex ,' an optimized version of GPT-5 as a coding agent, on September 15, 2025. GPT-5-Codex specializes in code review and refactoring, and can perform coding agent tasks with higher accuracy than GPT-5.

Introducing upgrades to Codex | OpenAI

https://openai.com/index/introducing-upgrades-to-codex/

The results of testing GPT-5 (light blue) and GPT-5-Codex (blue) on the SWE-bench benchmark, which measures the AI model's ability to resolve GitHub issues, are shown below. GPT-5-Codex performed slightly better overall, and in the code refactoring task, GPT-5 achieved 33.9% of the tasks, while GPT-5-Codex significantly outperformed it with 51.3%.

GPT-5-Codex also has a significantly lower probability of generating incorrect comments during code review.

GPT-5-Codex uses a mechanism that responds instantly to simple tasks and thinks for longer for more difficult tasks. The graph below shows the length of response time relative to the amount of input tokens. GPT-5-Codex responds faster than GPT-5 to small inputs and thinks longer than GPT-5 to large inputs.

GPT-5-Codex is already available as an extension called

the Codex IDE extension , which allows you to use Codex in various code editors. At the time of writing, it is compatible with Visual Studio Code, Visual Studio Code Insiders, Cursor, and Windsurf.

In addition, ' Codex CLI ', which allows you to use Codex within a terminal emulator, also supports GPT-5-Codex.

Additionally, by

enabling GPT-5-Codex in your GitHub repository , you can have GPT-5-Codex perform code reviews. The OpenAI development team is already using GPT-5-Codex to review the majority of pull requests, and it is working ahead of human review and is able to identify hundreds of issues per day.

GPT-5-Codex is available to ChatGPT subscribers of Plus, Pro, Business, Edu, and Enterprise plans. Usage limits vary by plan, with Plus, Edu, and Business plans covering a few intensive coding sessions per week, while Pro plans support multiple projects for a full week. Details of plan limits are summarized at the following link.

Codex Pricing
https://developers.openai.com/codex/pricing

OpenAI is working on making GPT-5-Codex available for use with other coding agents and will be releasing an API soon.

GPT-5-Codex is now live everywhere you use Codex—in your terminal or IDE, on the web, in GitHub, and in the ChatGPT iOS app.

We're working on optimizing GPT-5-Codex for use in other agentic coding tools, and will bring it to the API soon.

— OpenAI Developers (@OpenAIDevs) September 15, 2025