Codex
“The coding AI that comes with your ChatGPT plan” — ChatGPT’s hands-on partner that gets things done
What is Codex?
Codex is a coding agent from OpenAI. With the ChatGPT account you already use, it reads, edits, and runs code on the web, in the app, and in the terminal. Its biggest advantage: it is included in your plan, so there is no separate subscription.
- 1A coding agent that runs on your existing ChatGPT account
- 2Included in the free plan, so it is easy to try
- 3Same account on the web, desktop app, terminal, and IDE
What sets it apart
These are the differences we found by running the same material through several tools in our training sessions.
No separate payment
The official pricing page states that Codex is included in every ChatGPT plan, from Free to Go, Plus, Pro and Business, with only the usage limits varying by plan. If you already use ChatGPT, you can turn it on today.
Same account wherever you launch it
The web (chatgpt.com), the desktop apps for macOS, Windows and Linux, the terminal CLI, and the editor extensions all work with the same ChatGPT account. For example, you can pick up at home a task you started on your work laptop.
Almost no cost to try
The free plan is described as being for 'exploring Codex with quick coding tasks.' Light tasks are listed as possible starting with the $8 per month Go plan, so one or two people can try it out before the organization decides whether to adopt it.
⚖️ The weaknesses are clear, too
The official docs and pricing pages are both written around development work. Limits are framed as 'X local messages per 5 hours', which is hard to relate to non-developer roles. Codex is also tied to ChatGPT plans, so an organization that doesn’t use ChatGPT can’t easily choose it on its own.
💡 In plain EnglishIt’s less like hiring a new employee and more like putting work clothes on the assistant you already use and sending it out into the field.
Getting one more new tool approved in an organization is harder than it sounds. If you already use ChatGPT, Codex is the lowest barrier to seeing 'how an agent works' — no approval and no extra cost.
Same job, different approach
The internal request form page needs fixing, but the developer won’t have time until next week
The old way
- Write up a request and add it to the dev team’s queue
- Waiting with no idea when it will be done
- Make do with paper forms in the meantime
- Re-entering compiled results by hand
Together with Codex
- Turn on Codex with your ChatGPT account
- Describe in Korean what you want to change
- Review the changes first, then approve
- Developers only review it and move on
Common uses
Tweaking simple internal screens
Hand off small changes, such as adding a field to an application form or editing wording, just by describing them. Have a responsible team member confirm before anything goes live.
Build scripts for repetitive tasks
If you process the same data the same way every month, describe the procedure and ask Codex to turn it into something you can run in one step.
Reading code someone else wrote
Have it explain in Korean what a former employee’s files do. The result can serve as a draft handover document.
Who it’s for
Best for
- ✓Anyone already on a paid ChatGPT plan
- ✓Practitioners who want to try simple screen edits or automate repetitive tasks themselves
- ✓Owners who need to understand what inherited code does
Better served by other tools
- –Organizations that do not use ChatGPT
- –Anyone whose goal is automating document and Excel work, not code
- –Beginners put off by English screens and documentation
Can we use it at work?
The questions that adoption leads and security teams ask first.
Please note: Whether your input is used for training, and how long it is retained, varies by personal and business plan. Confirm this against the official terms.
10-minute quick start
- 1
Log in with the ChatGPT account you already use. You can look around on the free plan, too.
- 2
Try it on the web first, then install the desktop app once you are comfortable (macOS, Windows, Linux).
- 3
Connect the folder or repository you want to work on, and describe in Korean what you want changed.
- 4
Have it show you the changes first, and apply them only after you have reviewed them. Never apply changes without checking.
Copy-and-paste prompts
Replace only the [bracketed] parts, then paste it in.
Explain in Korean, in terms a non-developer can follow, what the code in this folder does overall. Summarize each file’s role in a table, and flag any parts that are risky to touch.
I want to add one [item] to the [screen name] screen. Don’t edit anything yet. First, show me a list of which files you would change and how. Once I say 'go ahead,' make the changes.
Every month I receive [source file], clean it up according to [processing rules], and save it as [output file]. Build this so the whole process runs in one go. If any value looks wrong along the way, have it stop and tell me.
Write a handover document in Korean for someone taking over this repository for the first time. Split it into three parts: what the system does, which areas change most often, and what can go wrong if they are edited incorrectly.
Search this folder for anything that should never leave the company, such as passwords, access keys or personal data. Tell me only the file names and line numbers. Do not print the values themselves.
Using it with other tools
Linking two or three tools changes your work more than any single tool does.
From idea to a working screen (half a day)
Understanding inherited code (one day)
Before you start
- Do not let it apply changes without confirmation. It is safer to ask for the list of changes first.
- Access keys and passwords embedded in your code may get uploaded along with it. Check for them first.
- Each plan has its own usage limit for every 5-hour window. When you hit the limit, your work stops midway.
- Code that runs is not necessarily correct. Have a responsible team member review it before it is used for real work.
Pricing: personal use and work use
Plans that individuals pay for are different from plans that organizations contract for by member.
For individual use
Exploring Codex with quick coding tasks
For light coding tasks
Use it on the web, in the CLI, in editor extensions and on iOS. Credits can extend your limits.
Much higher usage limits than Plus
Using it at work
Dedicated workspace, admin controls, SAML SSO and MFA
No fixed limits; credit-based billing and enterprise security features
Checked 21 Sep 2026 · US dollar amounts shown on OpenAI’s official Codex pricing page (learn.chatgpt.com/codex/pricing). Taxes and currency may vary by country. Prices change without notice, so check the official page before you pay. Official Codex pricing ↗
Agentic AI — the version that does the work itself
Codex is an agent in its own right. You can launch it in four places with the same ChatGPT account, so start with whichever feels most familiar.
Codex (Web)
Use it right in your browser. No installation is needed, which makes it the easiest way to try it for the first time.
- Log in at chatgpt.com, then open the Codex screen.
Codex desktop app
An app that works directly with folders on your computer and can run several tasks side by side.
- Download the app from the link in the official docs and install it (macOS, Windows or Linux).
- Open the app and log in with your ChatGPT account.
Codex CLI (terminal)
It runs in the terminal. Go into a folder and start with a single line.
- macOS·Linux —
curl -fsSL https://chatgpt.com/codex/install.sh | sh - After installing, run this in your working folder — codex
- The official documentation also covers installation on Windows, as well as via npm and Homebrew.
Installation steps and requirements follow the official documentation. Codex docs ↗ · Codex CLI installation docs ↗
Where Codex falls short
We don’t just list the positives. Here is what fell short when we used it.
- You can’t see how much usage you have left
Limits come in five-hour windows, and the screen doesn’t make it easy to see how much is left. If work stops in the middle of a busy stretch, you have to retrace how far it got.
- Few Korean-language hands-on materials
The interface and official docs are mostly in English, so there are still few Korean-language resources to turn to when you get stuck. You end up learning the terms by translating them one at a time.
- Too many entry points can be confusing
There are so many ways in (web, app, terminal and editor extensions) that you spend time at the start just deciding where to begin. The screens look different even though the job is the same.
Tools to compare
Claude CodeA coding AI that works in your terminal→
CursorAI pair-programming tool for developers→
ReplitA browser-based AI coding assistant→ChatGPTRebounding with Astra→FAQ
Last updated 22 Sep 2026 · The ratings on this page come from John Kim, CEO of Nanum Consulting, who has used these tools firsthand in training and real work.
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