Codex: a plain-English definition

Full explainer: What is OpenAI Codex? covers this in more depth, with examples and current plans.

What it means at work

OpenAI’s Codex documentation says you start with a goal, idea, or task and ChatGPT can gather context, take action, and produce something useful.

Plans and cost

• OpenAI’s Codex pricing page describes the Plus plan at $20 /month as power a few focused coding sessions each week. Plus covers Codex on the web, in the CLI, in the IDE extension, and on iOS.
• The Pro tier has plans at $100, $200, or $500 USD per month.
• Using an API key instead of a ChatGPT plan means you pay for Codex usage based on API pricing.
• Origin: the Codex paper introduces Codex, a GPT language model fine-tuned on publicly available code from GitHub. The same paper states that a distinct production version of Codex powers GitHub Copilot.

Safety defaults

The Codex security page from OpenAI says that by default the agent runs with network access turned off. OpenAI says that locally, Codex uses a sandbox that limits what it can touch. Its approval policy controls when Codex must stop and ask you before acting.

An example

You hand it a task such as reorganizing a folder of exported reports and producing a summary file. It works through the steps, including in the cloud when set up that way, and you review the output when it is done.

A common misconception

Codex is often filed under ‘developer tools,’ and its roots are there, but the pattern applies to any multi-step file or data task. Like any agent it needs a clear brief, limited access and a human check before you rely on the result.

Sources

• OpenAI, Codex, Overview: “Start with a goal, idea, or task. ChatGPT can gather context, take action, and produce something useful”
• OpenAI, Codex pricing: “Power a few focused coding sessions each week. $20 /month”
• OpenAI, Codex pricing: “Codex on the web, in the CLI, in the IDE extension, and on iOS”
• OpenAI, Codex pricing: “Plans at $100, $200, or $500 USD per month”
• OpenAI, Codex pricing: “Pay for Codex usage based on API pricing”
• arXiv, Chen et al., Evaluating Large Language Models Trained on Code: “Codex, a GPT language model fine-tuned on publicly available code from GitHub”
• arXiv, Chen et al., Evaluating Large Language Models Trained on Code: “A distinct production version of Codex powers GitHub Copilot”
• OpenAI, Codex, Agent approvals and security: “By default, the agent runs with network access turned off”
• OpenAI, Codex, Agent approvals and security: “Codex uses an OS-enforced sandbox that limits what it can touch”
• OpenAI, Codex, Agent approvals and security: “an approval policy that controls when it must stop and ask you before acting”