Installing Codex CLI on Mac: One Command Is All It Takes

Have you searched "install codex" before? The results come back in two flavors. One is the cloud version at chatgpt.com/codex, which runs entirely in your browser (Codex Web). The other is Codex CLI, which you install on your own machine. This guide covers the second one, installing Codex CLI on a Mac. Here's the short version: one line in the terminal is all it takes.

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

If you have never opened a terminal before, that's fine. This guide is built to be followed step by step: opening the terminal, running the install command, confirming it worked, signing in, and giving Codex its first task. Each step tells you what success looks like, so you can compare it against your own screen as you go. Install commands can go stale quickly, so if you get stuck, check the official docs as a second reference.

Codex CLI

Codex CLI is OpenAI's AI tool that takes instructions in plain language from your terminal. It reads, organizes, and edits files directly on your computer.

What you need: an account and macOS 12 or later

Three things: your regular ChatGPT account, a Mac running macOS 12 or later, and 4GB of memory or more (8GB recommended). If your Mac is from the last few years, memory isn't something you need to worry about.

Let's start with pricing, since it matters here. The official pricing page states in prose that Codex is included on every ChatGPT plan, including Free. The Free plan is described as a way to "sample Codex with quick coding tasks."

The terminal-based Codex CLI is a different story, though. In the same document's feature table, the CLI is only listed starting from the Plus plan, and the Free and Go cards don't list it at all. Having access to Codex and being able to run it from a terminal aren't the same claim.

The docs don't explicitly say whether CLI sign-in is blocked on the free plan. Since installing is one command and easy to undo, trying it yourself is faster than reading further. If it turns out to be blocked, Plus is the clear entry point where the CLI is confirmed in the feature table.

If you're on Windows, the install command is different. That gets its own guide.

Step 1: open the terminal

Press Command and the space bar together to open Spotlight search. Type "Terminal" and hit Enter. You can also find Terminal inside the Utilities folder within Applications.

Success looks like this: a white (or black) window appears with a blinking cursor. That window is your workspace for the rest of this guide. If you're curious about what a terminal actually is, you can set that aside for now: this guide only asks you to open the window and paste commands into it. If you want to build up terminal basics from scratch, there is a separate terminal setup lesson for that.

Step 2: run the install command

Copy the line below exactly, paste it into the terminal window, and hit Enter.

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

This one line does exactly one thing: it downloads and runs OpenAI's official install script. The script pulls Codex itself into a ~/.codex folder, and registers its location in your shell configuration (adding it to your PATH) so that typing codex works from any window. It's like ordering furniture and having the delivery crew assemble it for you before they leave.

Success looks like this: a handful of lines starting with ==> scroll by. There's no progress bar, so it's normal for the screen to go quiet for a moment. After that, you'll see a completion message like Codex CLI 0.149.0 installed successfully. followed by Start Codex now? [y/N], and you can just press Enter to skip past it. You'll open a fresh window to confirm the install in the next step. No icon appears in the Dock or Launchpad either, and that's expected, not a bug.

Step 3: confirm the install in a new window

Close the terminal window you have open, then open a fresh one the same way as Step 1. The registration you just set up only takes effect in windows opened after the install. In the new window, type:

codex --version

Success looks like this:

codex-cli 0.149.0

That output is from my own Mac, checked while writing this guide. The version number will differ depending on when you install. As of this writing (August 21, 2026), the latest version was 0.149.0. The number doesn't matter; as long as you see codex-cli in the output, the install worked.

Step 4: sign in with your ChatGPT account

In the same window, type just this:

codex

When it asks you to choose a sign-in method, pick Sign in with ChatGPT. Your browser opens automatically. Sign in with your usual ChatGPT account, and the flow hands control back to the terminal window. You only need to sign in once. After that, the session is remembered on your machine.

Success looks like this: Codex's chat prompt appears inside the terminal.

Step 5: give it one task

Type plain language into the prompt, not code. Try something like:

List the files in this folder for me

If Codex reads the folder and gives you an organized answer, you're done for today. When you want to update later, codex update is all it takes. If you want to build up your terminal fundamentals from the ground up, the AI CLI track covers it across six lessons.

Fixing "command not found" and duplicate installs

You typed codex and got "command not found." This is almost always a window issue. The registration only takes effect in windows opened after the install, so the window you used during install won't recognize it. Close the terminal completely and open a new one. If you're in a hurry, you can also run this in your current window to fix it immediately:

export PATH="$HOME/.local/bin:$PATH"
codex

Looks like Codex got installed twice. If you previously installed Codex through a development tool like npm or Homebrew, and then installed it again with this guide's method, you now have two codex commands with the same name. Whichever one comes first in your PATH is the one that runs. The install script itself flags this situation and warns you it's ambiguous which one will execute. Run which codex to see which one is currently active. It's safer to keep just one and remove the other. To remove the npm one, run npm uninstall -g @openai/codex.

Not sure what's wrong? Run codex doctor to check your install, configuration, and sign-in status.