How to use OpenAI Codex
Corbin Brown
2 min read
Codex is OpenAI's AI coding agent, and its quiet advantage is distribution: it's included with paid ChatGPT plans, which means millions of people already own a serious coding agent without knowing it. It comes in three forms — a terminal app (like Claude Code), an editor extension, and a cloud mode where agents work on their own machines while you do something else. Same brain, three places to point it.
Starting from zero
The terminal version is one install command (your existing agent — or the video above — can walk you through it), then you sign in with your ChatGPT account, open it inside a project folder, and type what you want in plain sentences. It reads the project, proposes changes, and asks approval before touching files or running commands. The approval prompts are the training wheels: read them for your first sessions and you'll absorb what the agent actually does — then loosen the reins as trust builds.
The workflow that separates pros from tourists
- Local for exploration, cloud for tickets. Work interactively when you're figuring out what you want; hand well-defined tasks to cloud Codex and review the pull request it sends back. The skill of writing a delegable task description is the skill.
- Give it standing instructions. Codex reads an AGENTS.md file in your project — house rules it follows every session. This is exactly the layer Boost OS installs: slash commands, guards, and memory that turn a raw agent into a disciplined one.
- Commit before big tasks. Same rule as every agent: a GitHub save point before a sweeping change is the cheapest insurance in software.
FAQ
Codex vs Claude Code — which one?
The honest answer: they leapfrog each other with every model release, and both are excellent. Deciding factors are usually which subscription you already pay for and which model's style you prefer. Many builders keep both installed and route tasks by mood and strength.
Do I need to know the terminal first?
No. You type sentences, not commands — the terminal is just the room the conversation happens in. Ten minutes in, the intimidation evaporates. If you'd rather stay graphical, the editor extension and the web version do the same job.