How do I install Codex CLI on a Mac?
Install Codex CLI on a Mac, sign in with ChatGPT, open an empty practice folder, and check your first safe session—without using live AEC files.
Direct answer
Answer
On a Mac, open Terminal and run OpenAI's official installer command. When it finishes, type `codex` and choose Sign in with ChatGPT. Start in an empty practice folder, then enter `/status` inside Codex to check the session. Use a read-only first prompt and keep live AEC project files out of this test.
Audience + setup
Before you start
- For
- Architects, designers, contractors, engineers, and AEC students installing Codex CLI for the first time · Mac users with little or no experience using Terminal or software-development tools
- Software context
- Codex CLI installation and first-run instructions checked against OpenAI's current macOS documentation on 26 August 2026.
- Prerequisites
- A Mac with an internet connection · A ChatGPT sign-in you are allowed to use with Codex · Permission from your office or school to install software · No live project files are needed
- Outcome
- Install Codex CLI on a Mac, sign in, open it in an empty practice folder, and complete one safe verification check.
01
What is Codex CLI?
Codex CLI is Codex inside a terminal window. Terminal is the text-based app already included with your Mac. Instead of clicking buttons, you type a short instruction and press Return.
Installing Codex CLI is only the setup step. A prompt is the message you give Codex for one task. A skill is a reusable workflow you can add later. This guide stops after installation and one safe check so you do not have to learn all three things at once.
02
What do you need before you start?
Use a Mac account that is allowed to install software, and have your ChatGPT sign-in ready. If your office manages the computer, ask the person responsible for IT or information security before you begin.
Do not use a live Revit, Rhino, AutoCAD, specification, contract, estimate, or client folder for this first test. You will make one empty folder called Codex-Practice instead.
- — A Mac and internet connection
- — A permitted ChatGPT sign-in
- — Permission to install software
- — About ten minutes
- — No coding experience and no project files
03
How do you make a safe practice folder?
Open Spotlight on your Mac, search for Terminal, and open it. Paste the two lines below into Terminal and press Return. The first line creates an empty folder in Documents. The second line moves Terminal into that folder. `$HOME` simply means your Mac user folder.
These commands do not delete or overwrite project files. If a folder named Codex-Practice already exists, the first line leaves it in place. Check that it is empty before continuing.
- — Open Terminal
- — Paste both lines
- — Press Return
- — Leave the window open for the next step
mkdir -p "$HOME/Documents/Codex-Practice"
cd "$HOME/Documents/Codex-Practice"04
How do you install Codex CLI on a Mac?
Paste the command below into the same Terminal window and press Return. This is the standalone macOS installer shown in OpenAI's current Codex CLI guide. It downloads an installation script from OpenAI's `chatgpt.com` domain and runs it.
Check the address before you press Return. It must read exactly `https://chatgpt.com/codex/install.sh`. Do not run a version copied from a different website. Wait for the installer to finish and read the final message before typing anything else.
- — Use the exact OpenAI address shown above
- — Press Return once
- — Let the installer finish
- — Read any permission or security message before accepting it
curl -fsSL https://chatgpt.com/codex/install.sh | sh05
How do you open Codex and sign in?
When the normal Terminal prompt returns, type `codex` and press Return. The first time Codex starts, OpenAI says you can choose Sign in with ChatGPT or another available sign-in method. This guide uses Sign in with ChatGPT.
Follow the sign-in instructions shown on screen. When the Codex conversation appears in Terminal, the installation and sign-in steps are complete. Do not approve access to another folder during this first test.
- — Type `codex`
- — Press Return
- — Choose Sign in with ChatGPT
- — Complete the sign-in instructions
- — Return to the Codex conversation in Terminal
codex06
How do you check that Codex is working?
Inside the Codex conversation, enter `/status`. OpenAI lists this as the command for checking the current session configuration. Confirm that you are still working in the Codex-Practice folder before asking Codex to do anything.
For your first prompt, type: `Tell me about this folder. Do not create, edit, move, or delete any files.` The folder should be empty, so Codex should have very little to report. The purpose is to confirm that a plain-language prompt works without changing a project.
- — Enter `/status` inside Codex, not at the normal Terminal prompt
- — Check the active folder or session information
- — Use the read-only practice prompt
- — Do not approve a file change for this test
07
What should you do next?
If Terminal says `codex: command not found`, close Terminal, open it again, return to the practice folder, and try `codex` once more. If it still fails, stop and use OpenAI's current documentation or your IT administrator rather than installing an unrelated package from a search result.
After this installation works, the next focused archiPrompt Learn guide is How do I install skills in Codex CLI? The related Agent skill cards below show real AEC workflow examples, but their current listings do not claim Codex compatibility. Read the asset type and compatibility on every listing before trying to use it with a tool.
- — Keep using the empty folder until you understand permission requests
- — Learn one short prompt before adding a skill
- — Read a listing's asset type and compatibility
- — Move to a sanitized project copy before any live AEC work
- — Keep human review in every project workflow
REVIEW BEFORE USE
Known limitations
- This guide covers the official standalone macOS route only. Windows, Linux, npm, Homebrew, team deployment, and managed-device setup need their own instructions.
- The official command downloads and immediately runs an OpenAI-hosted installation script. Use only the exact `chatgpt.com` address shown here, and stop if your firm or school blocks installation scripts.
- Removal is not part of this first-use guide because the correct removal route depends on how Codex was installed. Do not delete broad system folders; use verified package-specific instructions or ask your IT administrator.
- Codex can assist with AEC work, but an architect, engineer, contractor, BIM lead, or other responsible person must review outputs before they affect drawings, models, specifications, estimates, contracts, code decisions, or construction.
PRIMARY SOURCES
References used for this guide
These guides support Prompt evaluation and do not replace project-specific advice, code interpretation, consultant coordination, or qualified professional review.
Reviewed by archiPrompt Studio · Beginner AEC editorial + technical review