Codex Resources

guidebeginner4 min readVerified Mar 8, 2026

Guides, tutorials, comparisons, and documentation for OpenAI Codex — the AI coding agent that runs in your terminal, IDE, desktop app, and cloud.

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Codex Resources

OpenAI Codex is a coding agent that works everywhere you develop — in your terminal, your IDE, on the web, in GitHub, and as a desktop app. It can read, edit, and run code in sandboxed environments, create pull requests, review code, and handle multi-step engineering tasks autonomously.

What Is Codex?#

Codex is not just a code completion tool. It is an agentic coding system that can:

  • Read and understand entire codebases
  • Write features, fix bugs, and refactor code
  • Run tests and verify its own work
  • Create pull requests with proper commit messages
  • Review code for bugs, security issues, and style
  • Work in parallel across multiple tasks
  • Follow your project conventions via AGENTS.md
Info

Codex is included with ChatGPT Plus ($20/mo), Pro ($200/mo), Business ($30/user/mo), Edu, and Enterprise plans. No separate subscription required.

## The Codex Ecosystem

Codex runs across four surfaces, and they all share the same configuration:

| Surface | Best For | Platform | |---------|----------|----------| | Codex CLI | Terminal-native developers, automation, CI/CD | macOS, Linux, Windows (WSL) | | Codex App | Managing multiple agent threads, visual workflow | macOS, Windows | | IDE Extension | In-editor coding with agent capabilities | VS Code, Cursor, Windsurf | | Codex Cloud | Autonomous background tasks, PR generation | Web (chatgpt.com/codex) |

Models Powering Codex#

Codex uses purpose-built models optimized for software engineering:

| Model | Best For | Context Window | |-------|----------|----------------| | GPT-5.4 | Mixed workflows (code + reasoning + tools) | 1M (experimental) | | GPT-5.3-Codex | Pure coding tasks, intensive programming | 400K+ | | GPT-5.3-Codex-Spark | Quick edits, rapid prototyping | 128K |

For most tasks, start with GPT-5.4 — it combines strong coding, reasoning, and tool use in one model. Switch to GPT-5.3-Codex for intensive programming work where you want maximum code quality at lower cost.

Who Is Codex For?#

Codex works for anyone who writes or manages code:

  • Solo developers automating repetitive tasks
  • Freelancers accelerating client deliverables
  • Small teams running parallel coding tasks
  • Open source maintainers triaging issues and reviewing PRs
  • DevOps engineers building CI/CD automation

Getting Started#

Pick the setup path that matches how you work:

  • CLI Setup — Install Codex in your terminal (recommended for most developers)
  • App Setup — Set up the desktop app for multi-agent workflows
  • IDE Setup — Add Codex to VS Code, Cursor, or Windsurf

Or jump to Features to see what Codex can do, or Workflows for real-world use cases.

Open Source#

The Codex CLI is fully open source on GitHub, built in Rust and TypeScript. You can inspect the code, contribute, or extend it to fit your workflow.

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