Codex Guide
OpenAI’s coding agent, available through CLI, IDE and cloud workflows.
Last verified: · How we verifySuitable workflows
Developers evaluating a coding agent without making it their editor.
Limitations and billing
ChatGPT access and API billing are separate options. Features and limits depend on sign-in method.
Capabilities we verified
This is an evidence-based shortlist, not an exhaustive feature inventory. Omitted capabilities have not been checked for this record.
Pricing & usage
Paid from $8/mo
ChatGPT plan or API usage. The cost of metered usage or an external agent can be separate from the subscription.
Check official pricing ↗Models & access
Model access varies by ChatGPT plan or API credentials.
Verified families: GPT.
Official model information ↗Install and start the CLI
npm for the command below; standalone installers are also available for each desktop platform.
Installation command · npm
npm install -g @openai/codexOpen your project folder in a terminal, then run:
codexAccount and authentication
Run codex in your repository and complete the ChatGPT or API-key sign-in flow.
Project configuration and tools
Use AGENTS.md for project instructions and codex mcp to manage external tools. Review permissions before automation.
First task to try
Locate the project’s test command, explain the main modules, then review one small diff.
Script usage
This example asks for a project summary. Tool permissions still apply; a prompt is not a sandbox.
codex exec "Summarize the project structure without modifying files."Related CLI tools
All AI CLI tools →
Project evaluation checklist
- Open a small, familiar project and confirm that your essential language tooling works.
- Give the agent one bounded change with an observable acceptance criterion.
- Review the diff, run the project’s checks and compare the result with your current workflow.
- Inspect usage after the task. Estimate a month of similar work, including any separate model or agent bill.