OpenAI Codex Guide: Getting Started, Limits and Quick Answers
A practical guide to OpenAI Codex clients (CLI/IDE/web/desktop): session command cheatsheet, usage windows and reset mechanics, pricing and billing - verified against official docs and the /status output.
What is Codex and which clients ship it
"Codex is OpenAI's coding agent, included in every ChatGPT plan (including Free and Go) across four clients: Codex CLI (terminal), the Codex IDE extension, Codex web (chatgpt.com/codex) and the ChatGPT desktop app in Codex mode. Usage limits vary by plan; the authoritative source is chatgpt.com/pricing and the OpenAI Help Center."
10-second cheatsheet
- Check status and usage: type /status inside a Codex CLI session (shows remaining % and reset times)
- New session (keep terminal): /new; clear screen and reset context: /clear
- Compress a long session keeping key points: /compact; resume past sessions: /resume
- Switch account: /logout then sign in again; diagnose startup/connection issues: run codex doctor in the terminal
Topics covered in this guide
- Codex Reset Handbook - session, context or login: which "reset" do you mean
- Codex Usage Limits - windows, reset times and what to do when you hit them
- Codex Pricing - plans, credits and API cost estimation
- Codex vs Claude Code - coding agent comparison
Official sources (verification baseline)
- OpenAI Help Center "Using Codex with your ChatGPT plan" (help.openai.com)
- Codex developer docs (developers.openai.com/codex)
- Pricing page chatgpt.com/pricing; the /status output in your client is the first-hand source for your own quota
FAQ
How do I start using Codex?
Sign in with your ChatGPT account in any Codex client - install the CLI, or use chatgpt.com/codex. After authorization, run /status to confirm your account and quota state.
Can I use Codex for free?
Yes, the ChatGPT Free plan includes Codex with the tightest usage limits; higher tiers and credit packs raise your allowance. Current limits live at chatgpt.com/pricing.
Where do I type the slash commands?
CLI slash commands (/new, /clear, /status, ...) go into the Codex CLI session input; diagnostics like codex doctor run in your terminal before entering a session.