OpenAI Codex

Overview

Codex CLI is an official command-line AI coding assistant from OpenAI, built on the powerful GPT model family. Unlike regular ChatGPT, Codex is optimized for code generation and development workflows, with capabilities such as intelligent code generation and refactoring, cross-file understanding, and terminal command execution. In 2026 it added Computer Use (full-system control), Memory, ImageGen, and a 90+ plugin ecosystem in one push, evolving from simple code completion into an agentic coding tool.

Core features: official OpenAI product, GPT-powered, agentic coding, rich plugin ecosystem.

Installation

Codex CLI is installed globally via npm and requires Node.js >= 22. If the default registry is slow, you can switch to a mirror to speed up downloads.

# Install Codex CLI globally (requires Node.js >= 22)
npm install -g @openai/codex

# Speed up with a mirror (optional)
npm install -g @openai/codex --registry=https://registry.npmmirror.com

# Verify the installation
codex --version

Prerequisite: Node.js (>= 22) must be installed. Check with node -v.

Basic Usage

After installation you need to configure an OpenAI API key. Run codex in the terminal to start an interactive session, or launch it directly inside the VS Code integrated terminal to let it handle complex tasks like cross-file refactoring within your editor environment.

# Configure the API key
export OPENAI_API_KEY="sk-your-key"

# Start an interactive session
codex

# Run a task directly
codex "Refactor this React component to use Hooks"

# Launch inside the VS Code integrated terminal to pair with the editor

On Windows, set the environment variable in PowerShell with $env:OPENAI_API_KEY="sk-...".

Tips

In 2026 Codex added the /goal command for setting long-term goals and a Memory system for cross-session memory. Its plugin ecosystem can extend its capabilities (e.g. browser control, database operations). For complex cross-file refactors, let it read the relevant files first before issuing instructions; for sensitive projects, pay attention to the API key's permission scope and usage billing.

# Set a long-term goal
/goal Refactor the entire auth module to OAuth2

# List available plugins
/plugins

# Specify a model
codex --model gpt-4.1

Tip: OpenAI bills by usage; complex tasks can consume many tokens, so keep an eye on usage.

Configuration

Codex CLI is configured through the OPENAI_API_KEY environment variable, CLI flags, and an in-session /config command. Use --model to select a GPT model, and persist defaults in ~/.codex/config.toml. The /goal command sets long-term objectives and the Memory system carries context across sessions. Plugins (listed via /plugins) extend capabilities such as browser control and database access.

# Authenticate
export OPENAI_API_KEY="sk-..."

# Pick a model
codex --model gpt-4.1

# Persist defaults in ~/.codex/config.toml
model = "gpt-4.1"
auto_mem = true

# In-session configuration
/config          # open the settings panel
/plugins         # list and manage plugins
/goal Refactor the auth module to OAuth2

# Windows (PowerShell)
$env:OPENAI_API_KEY="sk-..."

OpenAI bills by usage; complex agent tasks can consume many tokens, so monitor usage in the dashboard.

FAQ

Common questions cover API key setup, model selection, plugin availability, cost, and the difference between Codex CLI and ChatGPT. Codex CLI is optimized for terminal-based coding workflows with agentic file editing and command execution, while ChatGPT is a general-purpose chat interface. Plugins and Computer Use extend Codex beyond code editing.

Q: How is Codex CLI different from ChatGPT?
A: Codex CLI is a terminal agent focused on code: it edits files, runs
   commands, and uses plugins/Memory for agentic workflows. ChatGPT is a
   general chat product.

Q: Can I use my own API key?
A: Yes—set OPENAI_API_KEY and Codex bills against your OpenAI account.

Q: How do I reduce token costs?
A: Use a smaller model for simple tasks, scope context tightly, and avoid
   long-running autonomous loops on expensive models.

Q: Does it work on Windows?
A: Yes; set the key in PowerShell with $env:OPENAI_API_KEY="sk-..." and
   run codex in the terminal or VS Code integrated terminal.

Q: What are plugins for?
A: Plugins add capabilities like browser control, database operations, and
   third-party API calls; list them with /plugins.

Keep an eye on the usage dashboard—agentic tasks can rack up tokens quickly.