Codex CLI

Codex CLI is a terminal coding assistant that works in your local repository on macOS, Windows and Linux. Developers can use it with models running locally through Ollama, including gpt-oss:120b, or connect to OpenAI through a paid ChatGPT account or API key. With OpenAI access, model requests go to the remote service even though file edits and commands run on your computer.

The agent can explain unfamiliar code, investigate bugs, edit files and run development tools already installed on your machine. Commands and diffs appear during the task, and you can steer work within the same session. A separate review mode checks uncommitted changes, a commit or differences against a base branch, returning prioritized findings without changing the working tree.

Interactive sessions suit ongoing repository work; noninteractive execution supports scripts and CI. Saved chats let you resume earlier tasks. Screenshots and diagrams can provide visual context, and subagents can investigate focused parts of a larger problem.

Skills hold reusable instructions. Plugins and local or remote MCP servers connect the agent to other tools and data. You can choose the model, reasoning effort and permissions for each run. Ollama's web-search service requires sign-in and uses an external service even with a local model.

The CLI is open source under Apache 2.0. Codex cloud is a separate hosted execution option: the CLI can submit work to a configured cloud environment and apply the resulting changes to your local repository.