How to Install OpenAI Codex CLI on Windows (and Fix 404 Not Found Errors)

Setting up your terminal environment for local AI-assisted engineering tools is amazing—until your initial installation command hits a roadblock. If you attempted to set up OpenAI Codex and were blocked by an registry error, you are not alone.

The Problem: npm error code E404

When running a guessed or outdated package command in the Windows Command Prompt, the npm registry throws a missing resource exception:

C:\Users\User>npm install -g @openai/codex-cli npm error code E404 npm error 404 Not Found - GET https://npmjs.org - Not found npm error 404 The requested resource '@openai/codex-cli@*' could not be found...

Why this happens: The package identifier name @openai/codex-cli does not exist on the npm server. The core executable CLI logic is bundled directly inside the foundational engine scope name.

The Solution: Step-by-Step Installation Guide

Follow these steps to clean up your environment registry context and download the correct global binaries securely:

1. Run the Correct Package Command: Open your terminal window and point npm to the official, integrated framework tool distribution location:
   npm install -g @openai/codex@latest
2. Verify Package Linkage Success: Once terminal dependency resolution completes, it will report the package structural allocation:
   added 7 packages in 31s
3. Query the System Shell Mapping: Confirm your system execution PATH variables accurately point to the newly registered node engine variables by checking the deployment version:
   codex --version
   You will see the active system architecture footprint print out cleanly:
   codex-cli 0.141.0

Launching Your Agent Environment

Now that the CLI is correctly linked to your terminal profile, you can open up your local interactive development session instantly by inputting:

codex --interactive

💡 Troubleshooting Tips for AI IDE Engineers

Missing Binary Fallbacks: On isolated Windows machines, if your global npm prefix scripts are blocked by Execution Policies, bypass npm completely. Head to the official repository releases, download codex-x86_64-pc-windows-msvc.exe, drop it into your local directory, and rename it to codex.exe.

Google Antigravity Mapping: If you are moving this workflow into the Google Antigravity IDE workspace, you don't even need npm dependencies! Use the internal extension channel path instead:

/plugin marketplace add obra/superpowers-marketplace
/plugin install superpowers@superpowers-marketplace