OpenAI · Codex
OpenAI Codex.
OpenAI's coding agent · CLI, IDE, desktop, web and cloud · one ChatGPT account
Codex is OpenAI's coding agent: it reads a repository, edits files across it and runs commands from plain-language instructions. Unlike its closest rival it has no separate price and no paywall — every ChatGPT plan includes it, the free one included. What the free plan does not include is a published limit, and past your allowance the unit becomes a credit that OpenAI never prices in money.
What it is.
Short version first: an agent that edits your repository and runs your commands, sold as a feature of a ChatGPT account rather than as a product with a price.
The thing to understand about Codex is that it is not one program. OpenAI ships it as a terminal CLI, an IDE extension, a mode inside the ChatGPT desktop app, a web surface, and a cloud runner that takes delegated tasks off your machine — plus code review on pull requests and a Slack entry point. They share one account and one usage allowance, and OpenAI's own documentation splits them into Codex Local and Codex Cloud, which is the split that matters for both permissions and price.
The CLI itself is open source under Apache-2.0 and installs with a single command, which reliably confuses the cost question. A free client is not a free tool: the licence covers the harness, and every turn still runs on OpenAI's models through either a ChatGPT plan or an API key. The two paths are not equivalent — on your own key the cloud-side features drop away, and code review, Slack and delegated cloud tasks are the parts you lose.
Which model runs underneath is configurable and not fixed. Workspace admins can set the starting model, the reasoning level and whether fast mode is available; individuals override per session where the workspace allows it. OpenAI has scheduled GPT-5.4 and GPT-5.4 mini to leave Codex for ChatGPT sign-ins on 31 August 2026, with GPT-5.6 Terra and GPT-5.6 Luna named as the replacements — your own API key is unaffected by that retirement.
One thing this page will not pretend. We have not run Codex ourselves: doing so means signing into an OpenAI account, and creating accounts is outside what this desk does. Everything below is read off OpenAI's own pricing, help-centre and repository pages on the date in the byline, plus two head-to-heads we worked through in full. Where a claim rests on documentation rather than a run, it says so — the same distinction our capability pages carry.
Seven ways to buy it and one way to get it for nothing, priced in four different units. The free tier is real and is not a trial; what it is not is documented as a number. The full breakdown, including what a credit turns out to be worth, is on the pricing page.
| Route | Bought as | Price |
|---|---|---|
| ChatGPT Go | Subscription | $8/mo |
| ChatGPT Plus | Subscription | $20/mo |
| ChatGPT Pro (5×) | Subscription | $100/mo |
| ChatGPT Pro (20×) | Subscription | $200/mo |
| ChatGPT Business seat | Per seat | $25/seat/mo $20/mo billed annually |
| Enterprise / Edu | Per seat | Contact sales |
| OpenAI API key | API key | At model rates |
When it is the wrong tool.
Five cases where the honest answer is something else. None of them is a complaint about quality — they are structural, they come off OpenAI's own pages, and no tier fixes any of them.
Two head-to-heads we have taken all the way through, both against tools people genuinely cross-shop. Each row says what the pair decides, because "which is better" is almost never the question anyone actually has.
| Pair | What it decides | Verified |
|---|---|---|
| Codex vs Claude Code | The like-for-like pair: two terminal agents from two frontier labs, so this one really is about model quality and price rather than shape. | 2026-08-13 |
| Codex vs Cursor | The quality-per-dollar question. One agent scores higher on a neutral index; the other finishes faster and far cheaper per task, and the gap survives holding the model constant. | 2026-08-13 |
If one of the five cases above is yours, the list of what to use instead — open-source options and self-hosted ones included — is on its own page, with every competitor's entry price read off the vendor's site and dated.
Frequently asked.
What people search next.