OpenAI is doubling down on making life easier for developers. Its latest tool, Codex, is an AI coding assistant that lives right inside ChatGPT, and it’s already turning heads.
If you’ve ever wished you had a junior developer who could write clean code, fix bugs, and run tests without burning out, Codex might be the sidekick you’ve been waiting for.
What Is Codex and What Can It Do?
Image Credit: OpenAI
Codex is powered by OpenAI’s codex-1 model, an upgraded version of the o3 model fine-tuned for software engineering.
The tool can:
- Write new code based on natural language prompts
- Fix existing bugs in your codebase
- Run and debug tests
- Explain confusing parts of your code
- Work across multiple tasks at once
Even better? It runs in a sandboxed cloud environment. So it’s secure, separate from your machine, and preloaded with your GitHub repo if you connect it.
Who Can Use Codex Right Now?
This coding tool is currently available to:
- ChatGPT Pro
- ChatGPT Team
- ChatGPT Enterprise users
Support for ChatGPT Plus and Edu users is coming soon.
At launch, users get “generous access,” but OpenAI says it will add rate limits later. Want more usage? You’ll be able to buy extra credits.
Using Codex Feels Like Working With a Teammate
Codex sits in the ChatGPT sidebar and is super simple to use:
- Give it a task by typing a prompt
- Click “Code” to start coding or “Ask” to get answers
- Track progress below the prompt bar
You can keep working on your computer while Codex does its thing in the background. It’s like having a focused, fast-moving teammate who doesn’t need coffee breaks.
Is It Safe to Use?
OpenAI built Codex with safety in mind:
- It operates in an air-gapped environment (no external internet or API access)
- It won’t write malicious code
- It uses AGENTS.md files to follow project-specific instructions
This keeps your data secure and the AI’s behavior predictable.
But It’s Not Perfect Yet
Like any AI tool, isn’t flawless. OpenAI admits that this tool, and even the best AI coding tools, can still make mistakes.
Microsoft’s research shows that even top-tier models sometimes struggle with debugging.
That said, Codex is already helping OpenAI’s internal teams with:
- Drafting documentation
- Building new features
- Automating repetitive tasks
So while it’s not a silver bullet, it’s a strong productivity booster.
Why Now?
AI-powered coding assistants are booming.
- Google’s Gemini Code Assist is stepping up.
- Anthropic released Claude Code.
- Cursor reportedly hit $300M in annual revenue in April.
And now, OpenAI wants its share of the spotlight, with Codex and a reported $3 billion acquisition of Windsurf, another AI coding platform.
What About Codex CLI?
OpenAI is also upgrading Codex CLI, its command-line agent, with the new o4-mini model. The pricing?
| Input Tokens (1M) | Output Tokens (1M) |
|---|---|
| $1.50 | $6.00 |
That’s about 750,000 words, or more than all the Lord of the Rings books combined, just to give you some perspective.
Final Thoughts
If you’re already using ChatGPT Pro or Team, Codex is worth exploring. Whether you’re a solo dev, working on a startup, or leading an engineering team, this coding tool could save you hours on repetitive work.
And if you’re not yet a subscriber?
This might be the nudge you need.
