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Verified Oct 12, 2026 · OpenAI Developers
Coding & app buildersOpenAI1 live
OpenAI Codex
OpenAI Codex is OpenAI's coding agent, included with every ChatGPT plan from Free to Enterprise. It runs in the terminal, in VS Code-style editors, in the ChatGPT desktop and web apps, on iOS and in isolated cloud environments. Developers use it to write, refactor and review code, sharing one usage allowance with ChatGPT Work.
Quick facts
Best for
- Developers already paying for ChatGPT
- Terminal-first engineers
- Teams automating code review
Key features
Codex CLI
A terminal agent that reads, edits and runs code locally, with sandboxing, approval rules and scriptable command-line options.
IDE extension
Works in VS Code, Cursor and Windsurf, while JetBrains IDEs and Xcode offer their own Codex integrations.
Codex cloud
Delegates tasks to isolated cloud environments with configurable dependencies and controlled internet access.
Code review and Slack
Reviews GitHub changes automatically and takes requests from Slack channels and threads on ChatGPT plans.
GPT-6 model family
GPT-6 Astra handles the hardest work, GPT-6.1 Sol comes close at a lower cost, and GPT-6 Luna gives the highest limits for lighter tasks.
Customization
Project guidance through AGENTS.md, plus skills, plugins, MCP servers and custom subagents.
Use cases
- Ask the CLI to fix a failing test suite and approve each command before it runs outside the sandbox.
- Hand a long refactor to Codex cloud and review the resulting diff later from the iOS app.
- Turn on automatic code review so every GitHub pull request gets a first pass before teammates look.
Pricing
Current deals
What is OpenAI Codex?
Codex is OpenAI’s agent for software work, tied to a ChatGPT account rather than sold on its own. OpenAI’s Codex documentation now lives in the ChatGPT docs, and Codex usage is shared with ChatGPT Work, so both draw from the same limits and credits.
Who it’s for
It fits developers who already pay for ChatGPT and want one subscription to cover chat and coding. Teams can add the Codex SDK, a GitHub Action and an app-server protocol to build Codex into their own tools and CI.
Limitations
- Limits are estimates, not fixed counts; long sessions, big codebases, fast mode and image generation use the allowance faster.
- Cloud chats can consume more of your limit than local messages.
- New models roll out in stages, so Free and Go users wait longer for the newest Sol model.
- API-key users lose cloud features, including code review and Slack.
OpenAI Codex FAQ
Yes, with limits. ChatGPT Free includes Codex for quick coding tasks, and Go at $8 a month covers lightweight work. Plus, at $20 a month, lists cloud integrations such as automatic code review and Slack.
OpenAI estimates 15 to 160 local GPT-6.1 Sol messages or 350 to 3,000 GPT-6 Luna messages per five-hour window on Plus, and 5 to 45 with GPT-6 Astra. Weekly limits may also apply, and cloud chats use more.
Yes. With an API key, Codex works in the CLI, SDK and IDE extension and is billed at API prices, but cloud features such as GitHub code review and Slack are not available.
OpenAI recommends GPT-6 Astra, GPT-6.1 Sol and GPT-6 Luna. GPT-6.1 Sol is rolling out to Plus, Pro, Business, Enterprise and Edu, while Free and Go use GPT-6 Luna. GPT-5.3-Codex-Spark was retired on September 14, 2026, and GPT-5.5 retires from Codex on October 14, 2026.
Alternatives to OpenAI Codex
Cursor
AI-first code editor with agents that plan, edit and run code.
GitHub Copilot1 live
AI pair programmer and coding agent inside your editor and GitHub.
Claude1 live
Anthropic's AI assistant for writing, analysis and coding, plus Claude Code and Cowork.
Cline
Open-source coding agent for VS Code and JetBrains that uses your own model keys.
Devin
Autonomous AI software engineer that takes tickets and opens pull requests.
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Guides
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Sources
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