Codex
#7 Codingby OpenAI · Best for ChatGPT subscribers
Also known as Codex AI, OpenAI Codex
Codex is OpenAI's software engineering agent: it works tasks in cloud sandboxes or your terminal, handles parallel task queues, and opens pull requests. It is bundled into every ChatGPT tier — limited use on Free, $8/month Go, $20/month Plus, and $100/month Pro — and since April 2026 usage is metered as token-based credits rather than per message. It pairs naturally with the rest of the OpenAI ecosystem.
Pricing
$8/mo (ChatGPT Go)
Bundled into ChatGPT plans; token-based credits, extra credits purchasable
Free tier: Yes · Open source: No
Strengths
- + Included with ChatGPT subscriptions most people already have
- + Parallel cloud tasks with PR integration
- + CLI and IDE options
Limitations
- − Plan limits constrain heavy professional use
- − Less terminal-workflow depth than Claude Code
Best for
How Codex works
Codex is OpenAI's software engineering agent. It works tasks in cloud sandboxes or in your terminal, handles parallel task queues, and opens pull requests when it is done. Its biggest practical advantage is distribution: usage is bundled into ChatGPT Plus at $20/month and the Pro plans, so for the millions of people who already pay for ChatGPT, it is effectively included rather than a new subscription.
Because it lives in the OpenAI ecosystem, Codex pairs naturally with the rest of the stack and offers both a CLI and IDE options. The parallel cloud task model means you can queue several jobs at once and collect PRs as they complete, which suits batches of small, well-defined tasks more than single deep refactors.
The limits are mostly about headroom. Plan limits constrain very heavy professional use, and it offers less terminal-workflow depth than Claude Code for developers who want a deeply hands-on agent. But for ChatGPT Plus and Pro subscribers, and for teams already standardized on OpenAI, Codex is a low-friction way to delegate parallel coding tasks without adding another tool to the bill.
What people use Codex for
Included coding for ChatGPT subscribers
Use the agent at no extra cost if you already pay for ChatGPT Plus or Pro, rather than buying a separate tool.
Parallel small tasks
Queue several well-scoped jobs in cloud sandboxes and collect pull requests as each one finishes.
OpenAI-stack teams
Standardize coding automation alongside the rest of the OpenAI tools your team already uses.
Codex pricing in context
At $8/mo (ChatGPT Go), Codex starts 60% below the $20/month median entry price for coding agents in this index. See the full AI agent pricing data for category medians and the verified pricing-change log.
Alternatives to Codex
Other coding agents in the index, ranked.
- 1.Claude CodeBest overall coding agent$20/mo
- 2.DevinBest for fully delegated tasks$20/mo + usage
- 3.CursorBest agentic IDE$20/mo
- 4.OpenHandsBest open-source optionFree (self-hosted) + API costs
- 5.GitHub CopilotBest for GitHub-native teams$10/mo
- 6.Replit AgentBest for non-developers$20/mo
- 8.Blackbox AIBest budget coding agent with model choice$10/mo
- 9.AtomsBest multi-agent app builder$20/mo
- 10.KiroBest for spec-driven agentic engineering$20/mo
- 11.JulesBest for asynchronous fire-and-forget coding tasks$19.99/mo
Codex FAQ
What is Codex AI?
Codex AI is a common way of referring to Codex, OpenAI's software engineering agent — the product name is simply Codex. It works tasks in cloud sandboxes or your terminal, handles parallel task queues, and opens pull requests. Usage is bundled into ChatGPT Plus ($20/month) and Pro, so most subscribers already have it.
Is Codex included with ChatGPT?
Yes. Codex usage is bundled into ChatGPT Plus ($20/month) and Pro plans, so existing subscribers get it effectively for free. Very heavy use can fall back to API pricing.
Where does Codex run?
It runs tasks in cloud sandboxes or in your terminal, supports parallel task queues, and opens pull requests, with both a CLI and IDE options available.
How does Codex compare to Claude Code?
Codex wins on distribution — it is included with ChatGPT and great for parallel small tasks. Claude Code offers more terminal-workflow depth for hands-on professional use. Many developers pick based on which subscription they already have.
What limits does Codex have?
Plan limits constrain very heavy professional use on the bundled tiers, and it is less deep on terminal workflows than some specialized agents. For occasional and parallel tasks it is well within those limits.