Overview
OpenAI Codex is a cloud-based coding agent that takes a task, executes it inside a sandboxed environment preloaded with your repository, and returns a pull request for your review. Rather than pair-programming like Copilot-style tools, Codex works asynchronously: you assign several bug fixes or features at once, switch to other work, and review the proposed changes when they land. It can spin up multiple agents simultaneously, which makes it effective for parallelizing routine engineering across a codebase.
Codex is not a standalone product. It is bundled into ChatGPT Free, Go, Plus, Pro, Business, Edu, and Enterprise plans, with usage limits scaling by tier - Plus includes Codex across web, CLI, IDE extension, and iOS, while Pro 20x ($200/mo) delivers 20x the Plus usage for heavy automation. A separate API-key path bills usage at standard OpenAI rates for CI and local SDK workflows, but drops cloud features like GitHub code review and Slack. The agent is powered by dedicated Codex models (GPT-5.3/5.4/5.5-Codex) and is backed by OpenAI’s rapid model iteration.
Key Features
- Parallel cloud agents that run multiple coding tasks at once
- Sandboxed environments preloaded with your repo; returns PRs
- Included with ChatGPT Plus/Pro - no separate subscription
- GitHub automatic code review and Slack integration
- API-key mode for CI/CD billed at standard OpenAI rates
Pricing
| Plan | Price | Codex access |
|---|---|---|
| Free | $0 | Limited trial access |
| Go (ChatGPT) | $8/mo | Lightweight tasks |
| Plus (ChatGPT) | $20/mo | Full local + cloud features |
| Pro (ChatGPT) | $100-200/mo | 5x-20x Plus usage |
| Business (ChatGPT) | $20-25/user/mo | Team admin + shared usage |
| Enterprise | Custom | Org-wide governance, SLA |
Comparison
Compared to Claude Code, Codex runs in the cloud and parallelizes better but requires a ChatGPT subscription and offers no local execution. Against GitHub Copilot, Codex is asynchronous and PR-focused rather than inline autocomplete, suiting reviewers over pair programmers. Versus Cursor, Codex trades the polished local IDE for managed cloud agents you can fire and forget.