Codex is now used by developers all over the world, from startups like Duolingo and Vanta to large enterprises like Cisco and Rakuten. Inside OpenAI, it’s become integral to how we build: nearly all engineers use Codex today, up from just over half in July. They merge 70% more pull requests each week, and Codex automatically reviews almost every PR to catch critical issues before they reach production.

The general availability of Codex reflects how quickly developers and teams everywhere are adopting it—and how much it’s already changing the way we build.

Tag @Codex in a Slack channel or thread and it will automatically gather the context it needs from the conversation, choose the right environment, and answer with a link to the completed task in Codex cloud. From there, you can merge its changes, keep iterating, or pull the task to your computer to keep working locally. Learn how to set up the Slack integration in the docs⁠(opens in a new window).

GPT‑5‑Codex was trained for Codex—specifically, the open-source agent implementation that powers the Codex CLI. We also tuned the agent implementation so that its prompt, tool definitions, and agent loop deliver faster and more accurate results with models like GPT‑5‑Codex.