On Friday, OpenAI announced the launch of a research preview of Codex, its most advanced AI coding assistant feature in ChatGPT.

Codex runs on codex-1, a special version of OpenAI’s o3 AI model, made specifically for coding tasks. According to OpenAI, Codex-1 writes cleaner code, follows instructions better, and can run and fix its code until it works correctly.

Codex operates in a secure, cloud-based virtual computer. If you link your GitHub account, Codex can access your code directly. It can perform tasks like writing simple features, fixing bugs, answering coding questions, and running tests usually in 1 to 30 minutes.

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It’s also designed to multitask, so you can keep using your computer or browsing the internet while it works in the background.

Who Can Use Codex?

Starting now, Codex is available to users with ChatGPT Pro, Team, and Enterprise plans. OpenAI says it will offer “generous access” for now but will soon introduce rate limits, where you may need to pay for extra usage. In the near future, Codex will also be available to ChatGPT Plus and Edu users.

AI tools for software development often called “vibe coders” are becoming very popular. Top tech companies like Google and Microsoft say that AI now helps write about 30% of their code. Other companies like Anthropic and Google have also launched or upgraded their own AI coding tools recently.

These tools are growing fast. For example, Cursor, another AI coding assistant, is now making around $300 million per year and is valued at $9 billion. OpenAI also just bought Windsurf, a major player in the coding AI space, for $3 billion clearly aiming to become a leader in this area.

How OpenAI Codex Works?

Codex appears in the ChatGPT sidebar. You can give it coding tasks by typing a prompt and clicking “Code,” or ask questions about your code with the “Ask” button. You can also see what tasks it’s working on and monitor progress.

Josh Tobin, OpenAI’s Agents Research Lead, said the goal is to make Codex act like a “virtual teammate”, handling tasks that would normally take human engineers hours or even days.

OpenAI is already using Codex internally to speed up repetitive tasks, build new features, and write documentation.

Safety and Limitations

Codex was built with safety in mind. It won’t help with requests to create malicious software and runs in a restricted environment without internet access or external APIs. This helps prevent misuse but can limit what the tool can do.

Still, like all AI tools, Codex is not accurate. AI coding agents often make mistakes. A Microsoft study showed that top models still struggle with debugging. But that hasn’t slowed down investment and interest in these tools.

Codex CLI and API Pricing

OpenAI also updated Codex CLI, a coding agent that works in your terminal. It now uses a smaller, faster model called o4-mini, which is also available via the OpenAI API for:

• $1.50 per 1 million input tokens
  
• $6 per 1 million output tokens
  

(For reference, 1 million tokens = about 750,000 words.)

Bigger Plan for ChatGPT

Codex is just one of several new tools OpenAI is adding to ChatGPT. Others include:

Sora (AI video platform)

Deep Research (research assistant)

Operator (web browsing agent)

These extras are designed to make ChatGPT more useful and attract more subscribers or encourage users to pay for more access, especially with tools like Codex.