#Installation & Login

#System requirements

Other requirements:

• Network access to OpenAI services
• Git (recommended for diff and checkpoints)
• Terminal: Windows Terminal, iTerm2, Kitty, etc.

#Install Codex CLI

#Method 1: Official install script (recommended)

macOS / Linux:

curl -fsSL https://chatgpt.com/codex/install.sh | sh

Windows (PowerShell):

powershell -ExecutionPolicy ByPass -c "irm https://chatgpt.com/codex/install.ps1 | iex"

Unattended install:

curl -fsSL https://chatgpt.com/codex/install.sh | CODEX_NON_INTERACTIVE=1 sh

#Method 2: npm

npm install -g @openai/codex

#Method 3: Homebrew (macOS)

brew install --cask codex

#Verify

codex --version

#Login

The first codex run prompts for authentication. Two options:

#1. ChatGPT account (recommended for individuals)

• Requires a plan that includes Codex (Plus / Pro, etc.)
• Configures the API key automatically
• Cloud features and quotas may differ from raw API billing—check official docs

#2. OpenAI API key

• Good for CI and pay-as-you-go enterprise use
• Create a key at platform.openai.com
• Some ChatGPT-only features may be unavailable

#Directories and environment variables

#IDE extension (optional)

• VS Code Marketplace
• Cursor, Windsurf, VS Code Insiders

After install, open the Codex panel in the sidebar and sign in with ChatGPT or an API key. Agent mode can read and write the project by default.

#Codex App (optional)

Download macOS / Windows installers from Codex Quickstart, select a project folder, and send your first message in Local mode.

#Troubleshooting

#codex: command not found

• Confirm the install script added the binary to PATH
• For npm global installs, ensure npm prefix -g is on PATH

#Unexpected Shell behavior on Windows

• Prefer official Windows sandbox docs: Windows setup
• Use WSL2 when you need a Linux-native toolchain

#Login failure or 401

• Check system time, proxy, and firewall
• Verify the API key is valid and Codex is enabled for your org

#Next steps

• Quick Start: interactive TUI and codex exec
• Config & CLI Reference: persistent sandbox and model defaults