OpenAI’s Codex App for macOS: Setup, Features & First Project

What is the Codex app?

The Codex app is OpenAI’s new macOS desktop application that allows you to build tools and automate tasks using AI agents, with no coding experience needed. The Codex app is built on advanced language models trained on both natural language and programming code, enabling it to understand your plain English descriptions and translate them into working solutions.

Note: Previously, Codex was only accessible through OpenAI’s API within IDEs like VS Code. If you want to learn about it, here is ourHow to use Codex guide.

Who is Codex app for?

The Codex app for Mac is designed for everyone, from complete beginners to experienced developers:

For non-developers: Create tools without learning programming—simply describe what you need and let the Codex app handle the implementation. Focus on solving problems, not writing code.

For beginners learning to code: The Codex app shows how your prompts translate into code, letting you ask questions and learn by doing with real examples. See exactly how AI interprets your requests and generates solutions.

For experienced developers: The Codex app accelerates development by handling boilerplate code, exploring new frameworks quickly, and automating repetitive tasks. Delegate routine work while you focus on architecture and complex problem-solving.

Now that you understand what the Codex app is and how it can assist you with your tasks, let’s get you set up and ready to begin building.

Setting up the Codex app on macOS

Getting started with the Codex app is straightforward. Let’s walk through the setup process.

Note: As we write this article, OpenAI has only released support for the Codex app on macOS (Apple Silicon).

Step 1: Download the Codex app

Open the Codex app website and download the macOS installer. The Codex desktop app is currently only available for Apple Silicon Macs (M1, M2, M3, or newer).

Step 2: Sign in with your OpenAI account

Once you’ve installed the Codex app on your Mac, launch it and sign in with your OpenAI account. If you have an existing ChatGPT or API account, use those same credentials. Click “Sign In” and enter your email and password.

Don’t have an account? Click “Sign Up”.

Step 3: Choose your subscription level

The Codex app is available under different subscription tiers:

• ChatGPT Free/GO: Limited usage, perfect for trying out the Codex app (available for a limited promotional period)
• ChatGPT Plus: Regular access with standard rate limits
• ChatGPT Pro, Business, Enterprise, and Edu: Higher rate limits and additional features

Review the options and select the one that fits your needs. The free tier is often sufficient for learning and testing out the Codex app.

Step 4: Complete initial setup

The Codex app may ask setup questions to personalize your experience:

• What do you want to build today?
• Are you a developer or new to coding?
• What types of projects interest you?

These help Codex provide relevant suggestions, but you can skip them if you prefer.

Step 5: Create your first project in the Codex app

The Codex app organizes work into projects or sessions:

• Click “New Project” or “Start Building”
• Give your project a name
• Optionally describe what you’re planning to build

This creates a dedicated environment for your work. You can have multiple projects for different tools.

Exploring the Codex app interface

Understanding the Codex interface helps you work efficiently. While layouts may vary with updates, most versions share common elements.

The main workspace

The Prompt Input Area:

This is where you communicate with the Codex app. Type instructions, change requests, or questions.

IDE selector :

Let’s you run Codex in different popular IDEs of your choice and run the implemented code by Codex AI.

The model selector:

The model selector allows us to choose the right model for our tasks. For now, use the special Codex models if you are using the Codex to implement your tasks.

Skill section:

Think of Skills as plug-ins or superpowers you can add to Codex so it can do real actions, not just chat.

Once you link a skill to the Codex app, Codex can access that app’s workspace and make changes directly within it.

Extra chat commands:

Click on the prompt bar and press “/“ to open the command menu. From here, select “Plan mode” for your project. Plan mode helps Codex break down a task into clear, ordered steps when you’re not sure what to do next or how to approach the problem.

Now that you understand the Codex app interface, let’s put it to work building something practical.

Building your first project with the codex app: A meal planner

Understanding what we’re building

In this hands-on tutorial, we’ll use the Codex app to create a meal planner that:

• Suggest meals based on dietary preferences (vegetarian, vegan, gluten-free)
• Organize recipes for an entire week
• Automatically compile ingredients into a shopping list
• Categorize items by grocery store section
• Calculate quantities based on serving sizes
• Allow easy customization and substitutions

Step 1: Starting the project and setting intent

In your Codex app workspace, start a new project. In the prompt area, clearly describe what you want to build:

Click here to view and copy the weekly meal planner prompt

I want to create a weekly meal planner website that helps me plan 7 dinners and generates a shopping list organized by grocery store sections (produce, dairy, meat, pantry, spices). I’m a vegetarian and prefer quick meals that take under 30 minutes to prepare. The planner should calculate ingredients for 2 people.

This includes:

• Scope: 7 dinners
• Output needed: Meal plan and shopping list
• Organization: Specified categories
• Constraints: Vegetarian, under 30 minutes
• Scale: 2 servings

The Codex app responds by explaining its understanding and asking a few questions about the tech stack before proceeding. We chose the option Codex recommended.

Note: If you have development experience, it’s always better to specify the tech stack you want Codex to use for your project in the prompt itself.

Codex might also ask you for your food preferences, which it sometimes asked for during our testing and sometimes didn’t.

Step 2: Executing the plan

Once you answer all the questions Codex asks, it returns with a plan that you can review, accept, or revise. In our case, the plan looked solid, so we chose to move forward with it.

Step 3: Reviewing the changes

Once you accept the plan Codex presents to you, it will begin executing it and return the file changes it made. Your task is to review the changes and see if the task was carried out as intended or not. If the task is not completed correctly or you want to suggest changes, you can use the same prompt bar to inform the Codex about your requests.

Let’s see how we can review and accept the changes:

Let’s try running the website it has provided us and see how well it has done the job with our single prompt.

Step 4: Asking for changes

It’s nearly impossible to get what we want in a single prompt using any kind of AI agent. Our main job starts after we get the initial project from the Codex app. We finally got the website we requested from Codex, but right now we can spot some problems with it, and it’s also missing a few features.

To solve this problem, we’ll simply go back to the Codex workspace and let it know all the changes that we are looking for. Here are the changes we requested from Codex:

I want to request a few changes to the website:

Right now, every meal card looks the same, and the boxes are different sizes, which doesn't look good.

Make the website feel more interactive. Right now, it's very static. I can think of some simple hover effects, and you can suggest more if you want.

The print meal button for a specific day and the download shopping list buttons are missing.

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Copy to clipboard

After the prompt is given, the Codex app will respond with all the changes it has made:

Let’s run the website again and see how effective the changes are.

We can see that Codex implements all our requests quite nicely, and not only that, it also selected different colors for each recipe palette, which solves our vague request of “every meal card looks the same.” This also demonstrates how smart Codex is when it comes to executing the tasks we give it.

You can repeat these steps to implement any type of project you want with the new Codex app. But remember, your prompt should be clear because prompts are the instructions Codex uses to understand the issue. If the prompt doesn’t have clear intent or information about the issue, Codex may not always be able to handle vague instructions as it did in our case.

Limitations of Codex app

Codex is a capable assistant, but it has important limitations you should understand, like:

• When Codex app generates code, it shows you what it would create without running it. Every suggestion requires your explicit approval. This means you can review solutions before committing, mistakes won’t affect your system, and you maintain complete control.

• Always test outputs thoroughly before relying on them.

• It has knowledge cutoffs and doesn’t know recent developments.

• Don’t share your passwords or authentication credentials.

• Be cautious with shopping habits, personal schedules, and identifying details.

• Clear instructions will always produce better results

Understanding these boundaries helps you use Codex effectively. Now let’s explore best practices.

Best practices for using Codex app

These practices will help you consistently achieve great results with the Codex app, whether you’re building personal projects or professional tools.

• Always keep your instructions simple and specific, for example:

Instead of: "Make a shopping list"

Write the prompt like: "Create a categorized shopping list organized by grocery store sections with quantities for 4 people."

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Copy to clipboard

• Always try to provide relevant context.

• Check for correctness, completeness, appropriateness, and your understanding before accepting.

• Use Codex for first drafts, then refine additional prompts and manual adjustments. Don’t expect perfection on the first try.

• Instead of one massive request, build incrementally. This makes verification easier and allows course correction.

With these practices in hand, let’s see what we’ve learned so far.

Conclusion

Congratulations! You now understand how to use the Codex app for macOS, how it works, and how to use it to create practical solutions for real-world problems.

What you’ve learned extends beyond meal planning. The same process applies to countless applications, such as organizational tools, budget trackers, wellness planners, educational resources, business utilities, and automation scripts.

To understand more about Gen AI consider taking these courses:

• Introduction to Generative AI (free)
• Generative AI for Everyone

Frequently asked questions

1. What is the Codex app?

The Codex app is OpenAI’s AI-powered assistant for creating code, tools, and digital solutions. Describe what you want in plain English, and Codex generates the implementation. It’s web-based and works for both developers and non-technical users.

2. Is Codex different from ChatGPT?

Yes. ChatGPT is designed for general conversation and questions, while the Codex app is purpose-built for creating code and building projects. The Codex desktop app provides a dedicated workspace for building, testing, and iterating on software projects with features like parallel agents, Automations, and Git worktree support

3. Can Codex replace a professional developer?

No. Codex assists with creation but isn’t a replacement for human expertise. It’s excellent for personal tools and prototypes, but complex systems require professional developers for quality, security, and reliability.

4. Does Codex execute or run the code it creates?

No. The Codex app generates code and shows what it would create, but you must explicitly review and approve before anything runs. This safety feature keeps you in complete control of your codebase and prevents unwanted modifications.

5. Can you use Codex on a Mac?

Yes, the Codex desktop app is available for macOS, specifically for Macs with Apple Silicon (M1, M2, M3, or newer chips). You can download the Codex app from OpenAI’s website and sign in with your ChatGPT account or OpenAI API key. The Codex app is currently exclusive to macOS, but Windows and Linux support is coming soon.

6. Is the Codex app free?

For a limited promotional period, the Codex app is available with ChatGPT Free and Go subscriptions so you can try it out. For regular, ongoing access, the Codex app is included in ChatGPT Plus, Pro, Business, Enterprise, and Edu subscriptions. There’s no separate charge for the Codex desktop app, it’s part of your ChatGPT subscription, with the option to purchase additional credits if you exceed your usage limits.

7. What is the Codex app in ChatGPT?

The Codex app is a separate desktop application from OpenAI that’s distinct from the ChatGPT chat interface. While you use your ChatGPT account to sign in to the Codex app, it’s a dedicated workspace specifically designed for coding and building projects with AI agents. The Codex app includes features not available in ChatGPT, such as running multiple agents in parallel, Automations for background tasks, built-in Git integration, and worktree support. Think of the Codex app as a specialized coding environment, while ChatGPT is for general conversation and questions.