OpenAI Codex CLI: terminal coding agent

Name: OpenAI Codex CLI
Author: OpenAI

At a Glance

Type

Developer tools

Pricing

FreemiumCLI is free (Apache-2.0); using it needs a ChatGPT plan (Free, $8 Go, $20 Plus, from $100 Pro, ~$20-25/user Business) or metered API billing, in USD.

Best For

Running an OpenAI coding agent against a local repo from the terminal or CI, to write, edit and test code without leaving the shell.

Platforms

CLI, macOS, Linux, Windows, API

Models

GPT-6 Sol, GPT-6 Luna

Founded

2015

Headquarters

San Francisco, California, United States

Free Tier

Available

API

Available

Licence

Open Source

Key Features

Open-source terminal coding agent, Apache-2.0 licensed, maintained in the openai/codex GitHub repository

Installs via curl/PowerShell script, npm (@openai/codex), a Homebrew cask, or a binary from GitHub Releases

Runs on macOS (Apple Silicon and x86_64), Linux (x86_64/arm64) and Windows

Authenticates with a ChatGPT account (Plus, Pro, Business, Edu or Enterprise) or an OpenAI API key

Uses OpenAI's current Codex models, including GPT-6 Sol and GPT-6 Luna, per OpenAI's docs

Includes sandboxing and agent-approval controls that gate which commands it can run, per OpenAI's docs

Connects to GitHub (with pull-request support), GitLab (beta), Slack, Linear and MCP servers

Also ships as an IDE extension, a cloud Codex environment and a desktop app, alongside the CLI

Pros & Cons

Strengths

Free to install and open source under Apache-2.0, so the code can be audited or modified.
Works from either a ChatGPT subscription or a pay-as-you-go OpenAI API key, with no separate CLI licence.
Native installers for macOS, Linux and Windows, plus npm and Homebrew packages.

Limitations

Real use needs a paid ChatGPT plan ($20/month Plus or higher) or metered API billing — the free ChatGPT tier is rate-limited, per learn.chatgpt.com/docs/pricing.
It executes shell commands and edits files directly, so sandbox and approval settings need reviewing before granting broader permissions.
Underlying model names and pricing have changed repeatedly through 2026 (e.g. GPT-5.5 is being retired on 14 October 2026), so specifics date quickly.

What it is

Codex CLI is OpenAI's open-source terminal coding agent, published as the openai/codex GitHub repository under an Apache-2.0 licence. It runs on the developer's own machine, reading a local repository, proposing edits, and executing shell commands on request, rather than working through a chat window in a browser.

Interface and dependencies

Install it with the official curl (Mac/Linux) or PowerShell (Windows) script, via npm install -g @openai/codex, through a Homebrew cask, or by downloading a binary from GitHub Releases. It runs natively on macOS (Apple Silicon and Intel), Linux (x86_64/arm64) and Windows. To do any work it needs either a ChatGPT account on a Plus, Pro, Business, Edu or Enterprise plan, or an OpenAI API key billed per token; there's no way to run it against OpenAI's models for free indefinitely, since the free ChatGPT tier is rate-limited. OpenAI's docs list GPT-6 Sol and GPT-6 Luna as the current models behind it, alongside sandbox and approval-policy settings that control what commands it can run without asking first.

Where it fits

It's aimed at developers who want an agent operating directly on their filesystem and shell — writing patches, running tests, or working through a defined task list — rather than copying code in and out of a chat UI. The same underlying service also ships as an IDE extension, a cloud environment and a desktop app, and connects to GitHub, GitLab (beta), Slack, Linear and MCP servers, but the CLI is the locally-run entry point aimed at terminal-based workflows.

Frequently Asked Questions

Do I need a ChatGPT subscription to use Codex CLI?

No. OpenAI's docs say you can authenticate with an OpenAI API key instead and pay per token, rather than using a ChatGPT plan.

Is Codex CLI itself free?

The CLI is free and open-source under Apache-2.0. Running it against OpenAI's models needs either a ChatGPT plan (a rate-limited $0 free tier, then $8 Go, $20 Plus, from $100 Pro) or metered API usage, per learn.chatgpt.com/docs/pricing.