ChatGPT Codex, OpenAI's First Cloud Software Engineering Agent

Michael Willson
May 25, 2025

ChatGPT Codex is OpenAI’s new cloud-based software engineering (SWE) agent that helps you write, debug, test, and manage code faster than ever. It can run code in the cloud, work with GitHub repos, and fix bugs on its own. If you’re a developer or part of a team building apps, Codex can save hours of manual work every week.

In this article, you’ll learn what ChatGPT Codex is, how it works, what makes it different from tools like GitHub Copilot or Devin, and how you can start using it today.

What is ChatGPT Codex?

ChatGPT Codex is an AI software engineer built by OpenAI. It’s available inside ChatGPT for Pro, Team, and Enterprise users. Codex helps automate software development tasks like:

Writing and editing code
Fixing bugs
Running unit tests
Making pull requests
Managing code in real time

It works entirely in the cloud. That means it runs your code, checks results, and gives updates—all without needing to install anything on your machine.

Key Features of ChatGPT Codex

1. Cloud-based execution

Codex spins up a secure cloud workspace for each task. It can install dependencies, run code, and even test it in real time.

2. GitHub integration

It connects with GitHub repos, so it can pull the latest code, make changes, push updates, or create PRs automatically.

3. Multi-step task handling

Codex doesn’t just answer a coding question. It can handle long tasks end-to-end—like finding a bug, fixing it, testing the fix, and reporting the result.

4. Natural language control

You don’t need to write perfect prompts. You can just say, “Fix the bug in login.js” or “Add a forgot password feature”—and Codex figures it out.

How ChatGPT Codex Works

When you ask Codex to fix or build something, it does a few things behind the scenes:

It creates a cloud environment (virtual workspace)
It pulls your repo (if connected)
It performs the task (bug fix, feature, test)
It gives you a summary of what changed, including code diffs and test results

This all happens live. You can watch the steps as they run, and even stop or modify them mid-way.

Codex vs Copilot vs Devin

Here’s how Codex compares to GitHub Copilot and Devin:

Real Use Cases of ChatGPT Codex

Bug fixing

Ask Codex to “Fix the error in payment.js” and it will scan the file, identify the issue, run the fix, test it, and show the results.

Code reviews

Codex can look through your pull requests and suggest changes or optimizations, using best practices and logic.

Feature creation

You can say “Add a dark mode toggle” or “Build a new settings page” and it’ll generate the required files, update components, and test them.

Test generation

Codex can create test files for your React components, API routes, or backend functions—then run them until they pass.

Why Developers Are Excited

Saves hours of repetitive work
Reduces human error in testing and debugging
Great for solo developers or small teams
Makes onboarding new devs faster by documenting changes

Who Can Use ChatGPT Codex?

Codex is currently available for:

ChatGPT Pro users
ChatGPT Team accounts
ChatGPT Enterprise clients

OpenAI has said it will expand availability to more plans soon, including ChatGPT Plus and education partners.

How to Access and Use It

Open ChatGPT (Pro, Team, or Enterprise)
Choose the “Codex” AI assistant from the list
Link your GitHub repo if needed
Start asking it to build, fix, test, or explain code

You can also upload files or paste code directly. Codex will remember context throughout the session.

Codex Task Capabilities

Certifications to Boost Your Skills

To get the most from tools like Codex, it helps to understand how AI and data systems work behind the scenes. Here are three trusted certifications:

Final Thoughts

ChatGPT Codex isn’t just a coding assistant—it’s a full cloud-based AI engineer that can handle everything from bug fixing to repo management. It helps developers save time, stay consistent, and focus on bigger ideas.

Whether you’re a solo founder, startup dev, or part of a growing team, Codex is like having another engineer on call 24/7.

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ChatGPT Codex, OpenAI’s First Cloud Software Engineering Agent