AI-powered coding agent for faster, higher-quality development.
Codex for Builders
What is Codex?
Codex is OpenAI’s agentic software teammate designed to accelerate builder productivity and ultimately enable fully autonomous execution of software tasks.
Where can you use Codex?
Codex works where developers build and write code. Codex is one unified agent, one product, with clients for the places developers work.
In your terminal with the open source Codex CLI
On the web with Codex web
On your phone, with the Codex tab in the ChatGPT iOS app
In your IDE with the Codex IDE extension
In GitHub with the GitHub integration
What do builders use Codex for?
Familiarizing with new or large codebases.
Drafting technical designs and docs
Debugging issues and exploring solutions
Planning and implementing migrations and new features
Leveraging Codex CLI’s headless mode for more advanced use cases around CI/CD automation
How does Codex tie in with my ChatGPT plan?
You can sign in to the CLI and IDE directly through your ChatGPT plan, eliminating API key setup. Codex web is available in ChatGPT as well after you connect your GitHub account
What is the best model to use with Codex?
Codex now leverages the recently launched GPT-5-Codex model, a version of GPT-5, that is built for agentic coding use cases. A few highlights:
More steerable: Writes high-quality code on complex engineering tasks without lengthy instructions.
Adaptive reasoning level: Adjusts reasoning time to task complexity. It’s snappy in interactive sessions and can work independently for multiple hours.
Excellent at code review: Trained to conduct code reviews, navigate codebases and run code and tests to validate correctness.
Supports image input: Use images or screenshots to guide frontend work, visually inspecting progress and catching issues in the cloud.
Purpose-built for coding: Purpose-built for Codex CLI, IDE, cloud, and GitHub, and focuses on agentic coding tasks.
Key benefits for builders
Code generation from natural language: Quickly scaffold projects, add features, or generate boilerplate code.
Code understanding: Get clear explanations for complex logic and dependencies.
Refactoring & optimization: Improve efficiency and maintainability without altering intended behavior.
Multi-language support: Works across popular programming languages, frameworks, and libraries.
Automating repetitive tasks: Offload well-scoped engineering work like refactoring, renaming, and writing tests to stay focused on higher-value work.
Core resources
OpenAI Codex demo: Understand the basics of using Codex and understand how Codex’s IDE extension, Codex web, and code review work in unison to help builders accelerate their workflows.
Codex overview & tips: Public documentation with capabilities, usage tips, and an overview video.
Developers hub: Central resource for Codex docs, guides, and API references.
