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ChatGPT Codex App Guide 2026｜Download, Install, Sign In & Get Started for New Users (with Screenshots) ​

The Codex App is OpenAI's official AI coding agent desktop client, available on macOS and Windows. This guide is for first-time Codex users: download it from the official source, install it, sign in with your ChatGPT account, and tour the interface — about 10 minutes total.

TL;DR: Installing Codex takes four steps — Prepare an account → Download → Install → Sign in. Three things to know up front: ① official downloads are only chatgpt.com/codex (or openai.com/codex) and the app stores — avoid third-party installers; ② Windows is fully supported (released March 2026), despite older tutorials claiming otherwise; ③ free accounts work but are limited — full features (parallel agents, Skills, Automations) need Plus or above.

Contents:

  1. What Is the Codex App?
  2. What to Prepare Before You Start
  3. Download and Install Codex
  4. Sign In with Your ChatGPT Account
  5. First Steps: Tour the Codex Interface
  6. Pricing and Limits (2026)
  7. FAQ

What Is the Codex App? ​

The Codex App is an AI coding agent desktop client from OpenAI. It's fundamentally different from code completion tools like GitHub Copilot — a completion tool suggests while you write, but Codex works on its own: it reads code, edits files, runs tests, fixes bugs, and generates pull requests, and it can run multiple agents in parallel on different tasks.

Codex is already built into ChatGPT; the desktop App is its graphical "command center": projects and chats on the left, the workspace in the middle, and a code review panel on the right. Core features:

  • Parallel Agents: run multiple agents on different tasks at the same time
  • Isolated Worktrees: each task runs in its own workspace so they never interfere
  • Review Panel: inspect diffs before merging into the main codebase
  • Automations: hand repetitive work to agents on a schedule
  • Skills: connect agents to tools and workflows

Codex runs on the GPT-5.6 family of models (Sol / Terra / Luna; the coding-optimized model matches what's in ChatGPT). Free accounts use Terra only; Plus and above can switch between all models — see our GPT-5.6 usage guide.

ChatGPT Codex App interface screenshot

What to Prepare Before You Start ​

  • ☐ A macOS or Windows computer: Windows needs 10 (build 19041+) or 11
  • ☐ A ChatGPT account: if you don't have one, register first. New ChatGPT registration no longer requires phone verification, but Codex sign-in may still ask (see FAQ)
  • ☐ Plus or above recommended: free accounts are feature-limited
  • ☐ A stable network: keep it stable through download and sign-in

Download and Install Codex ​

Only download from the official website or official app stores:

macOS ​

  1. Open chatgpt.com/codex (or openai.com/codex)
  2. Click "Download for macOS" to get the .dmg, open it, and drag the Codex icon into the Applications folder
  3. If macOS shows a "can't verify developer" warning, go to System Settings > Privacy & Security and click "Open Anyway"

Codex official download page

Codex download page — click to download

Windows ​

  1. Open chatgpt.com/codex and download, or search "Codex" in the Microsoft Store (verify the publisher is OpenAI)
  2. Or install from the command line: winget install --id OpenAI.Codex
  3. System requirements: Windows 10 (build 19041+) or Windows 11

Codex installer screen

Safety reminder: never install Codex from third-party download sites — disguised installers can carry malware. Only use the official website, Microsoft Store, or App Store.

Sign In with Your ChatGPT Account ​

  1. Open the Codex App and click "Sign in"
  2. Choose "Sign in with account"; your browser opens the OpenAI login page
  3. Sign in with your ChatGPT account, authorize, and return to the app — you're in

Codex sign-in method selection page

OpenAI sign-in page

Authorize Codex and continue

About phone verification: OpenAI has removed phone verification for creating new accounts / using ChatGPT, but Codex may still require phone verification on a new device, after a reinstall, or when a session expires. If that happens, first confirm your account can sign in to ChatGPT normally; if your account has no valid phone number, enable two-step verification (MFA) in ChatGPT settings — this usually bypasses the SMS check.

First Steps: Tour the Codex Interface ​

After signing in, you'll see these areas — one look and you'll know where to start:

  • Left sidebar: Projects and Chats
  • Conversation area: describe a task in the input box; Codex reads code, edits files, and runs tests
  • Parallel agents: run multiple agents at once, each on its own task
  • Review panel: check per-file diffs before merging into the main codebase
  • Worktrees: each task runs in an isolated workspace, so switching projects never pollutes each other

To actually get going, click "Projects" in the left sidebar, create a project, drop your code in, and give Codex one small, clearly defined task to try.

Pricing and Limits (2026) ​

Codex isn't sold separately — it's bundled into every ChatGPT plan:

PlanPriceCodex Access
Free$0/moBasic features, low limits (Terra model only)
Go$8/moMore than Free, still limited
Plus$20/moFull features — the starting point for most solo developers
Pro 5x$100/mo5x the Plus limits
Pro 20x$200/mo20x the Plus limits
Business$20/user/mo+Same as Plus + team management

Limits are counted in a rolling 5-hour window and, since 2026, metered by token-based credits: the same command costs far fewer credits for a small change than for a large refactor, so "30–150 messages" can mean very different amounts of actual work. When you run out, wait for the window to reset or upgrade your plan.

For a detailed limit comparison, see our Codex limits guide and Plus vs Pro comparison.

FAQ ​

Q: Does the Codex App support Windows? A: Yes. OpenAI released the Windows version in March 2026. Install from the Microsoft Store or with winget install --id OpenAI.Codex; Windows 10 (19041+) or 11 is required.

Q: Does signing in to Codex require phone verification? A: OpenAI has removed phone verification for creating new accounts and using ChatGPT, but Codex may still ask for it on a new device or after a reinstall. If it happens, first confirm your account can sign in to ChatGPT, or enable two-step verification and retry.

Q: Can I use the Codex App with a free account? A: Yes, but features are limited and limits are low (Terra model only by default). Parallel agents, Skills, and Automations require a Plus plan or above.

Q: What's the difference between Codex App and GitHub Copilot? A: Copilot is a code completion tool that suggests as you type; Codex is an autonomous coding agent that can read code, edit files, run tests, fix bugs, and generate pull requests on its own.

Q: What's the difference between the Codex App and Codex CLI? A: The Codex App is a graphical desktop client (project management, parallel agents, review panel); the Codex CLI is a terminal-based tool for developers who prefer the command line. Both share the same Codex capabilities and can migrate config and history between them.