Codex unifies into "a single agent experience" with IDE extension and dedicated model "GPT-5-Codex"
On August 27, 2025, OpenAI announced “GPT-5-Codex,” a new model further optimized for code generation and review, along with the “Codex IDE extension” for use in VS Code, Cursor, and other editors. At the heart of this update is bringing together the Codex experience — previously scattered across the terminal (Codex CLI), the cloud, IDEs, GitHub, and the ChatGPT app — into a single unified product connected through one ChatGPT account.
Details
- GPT-5-Codex: A model built by further optimizing GPT-5 for software engineering. Dynamically adjusts how much time it spends thinking based on task complexity, responding quickly to simple requests while taking its time on complex work. Particularly strong at code review, refactoring, and frontend development
- Codex IDE extension: Offered as an extension for major editors like VS Code and Cursor, letting users preview and edit local changes on the spot while using the Codex agent. Cloud tasks can now also be managed from within the IDE
- GitHub code review: Added a feature that automatically reviews pull requests, analyzing the code’s intent, dependencies, and test results to verify whether the PR’s stated intent matches the actual diff
- Unified experience: Reorganized so Codex can be accessed with the same ChatGPT account from the terminal, IDE, web, GitHub, or the ChatGPT iOS app
- Availability: Included with ChatGPT Plus, Pro, Business, Edu, and Enterprise plans. API access to GPT-5-Codex began on September 23, 2025
- Rapid growth: GPT-5-Codex processed more than 40 trillion tokens within just three weeks of release, later disclosed as one of the fastest-growing models in OpenAI’s history
What happened next
This unification cemented Codex’s shift from “an experimental agent in the cloud” into “a product embedded in developers’ everyday workflows.” About a month and a half later, in October 2025, Codex officially moved to general availability (GA) at OpenAI’s DevDay, adding Slack integration and admin tools that accelerated enterprise adoption in earnest.