Codex CLI: OpenAI's terminal coding agent and how to install it

A coding agent for the command line

According to a guide published on dev.to, Codex CLI is a lightweight code agent developed by OpenAI that runs locally in your computer's terminal. The command-line tool is also just one part of a broader family: OpenAI ships integrations for code editors such as VS Code, Cursor and Windsurf, a desktop application referred to as the codex app, and a cloud-based option called Codex Web.

Who it is for

The guide frames the tool as being aimed at people who develop software and want an AI coding assistant directly on the command line of their operating system, with support spanning macOS, Linux and Windows.

Two authentication paths are supported. You can sign in with a ChatGPT account — the guide lists the Plus, Pro, Business, Edu and Enterprise plans — or configure an OpenAI API key instead, which is the natural route for anyone who wants to work outside a ChatGPT subscription.

Several ways to install it

Installation varies by platform, and the dev.to article walks through the main options:

• On macOS and Linux, the tool can be installed by running an official shell script fetched with curl.
• On Windows, an equivalent one-line PowerShell command is provided.
• Package manager users can install it globally from npm with npm install -g @openai/codex, or on macOS via Homebrew with brew install --cask codex.
• Standalone executables are also available for manual download from the project's releases on GitHub.

The project's source repository is hosted on GitHub under the openai organization as codex, which is also where the release assets live.

Starting out

Once installed, getting started is a single command: run codex in the terminal. On first launch you choose how to authenticate — either log in with your ChatGPT account or set up an API key — after which the agent is ready to work from the shell. The dev.to guide also points to a short video overview for anyone who wants to see the tool in action before committing to an install.

Why it matters

The piece is a useful reminder that OpenAI's coding agent strategy is not confined to a chat window or a single IDE. By shipping the same agent as a CLI, editor integrations, a desktop app and a web version, OpenAI covers both developers who live in the terminal and those who prefer a graphical environment. The terminal client is the piece that slots most naturally into scripts, remote SSH sessions and existing shell workflows.

For developers evaluating local AI coding agents, the practical appeal here is the low barrier to entry: familiar installation routes through npm and Homebrew, coverage of the three major operating systems, and a choice between an existing ChatGPT subscription and an API key. Anyone already on a paid ChatGPT plan can sign in with the account they have, while API-key users can fold the tool into their existing OpenAI setup.