The definitive bilingual (🇰🇷 KR / 🇺🇸 EN) guide to OpenAI Codex
CLI · Desktop App (macOS/Windows) · IDE Extension · Web Dashboard
Last updated: April 23, 2026
The live site displays the viewer's current date automatically and reflects the latest Codex model guidance reviewed from official docs.
Codex 101 is a comprehensive guide to OpenAI's coding agent Codex, organized for both first-time users and advanced practitioners.
Based on the official OpenAI documentation and OpenAI Docs MCP lookups, the guide is manually reviewed and verified before publication.
- First-time users: Start with sections 04-06 (setup, sign-in, first run), then 10 (approval/sandbox basics), and 14 (OpenAI Docs MCP).
- Professional users: Start with sections 12-14 (AGENTS.md, config.toml, MCP), then 15-17 (session strategy, automation, prompting contracts).
- Re-checking
codex/modelsshows the main change today:gpt-5.5is now the top recommended Codex model when it appears in your model picker. During rollout,gpt-5.4remains the fallback,gpt-5.4-ministays the fast local/subagent lane,gpt-5.3-codexremains the cloud/code-review lane, andgpt-5.2is still the main alternative model. - The latest model guidance is more nuanced than a simple replacement story.
gpt-5.5is currently a ChatGPT-authenticated Codex model rather than an API-key path model, sogpt-5.4is still the most important broadly available flagship and the practical default when GPT-5.5 has not rolled out to an account yet. - Quickstart and Pricing remain the most important moving pieces. Quickstart still says every ChatGPT plan includes Codex and prefers the App path on desktop platforms, while Pricing now includes
GPT-5.5usage and credit tables. On Plus, the published local-message ranges aregpt-5.515-80,gpt-5.420-100,gpt-5.4-mini60-350, andgpt-5.3-codex30-150. The docs also explicitly note that GPT-5.5 is more token-efficient for comparable work, but that API-key sign-in still does not expose GPT-5.5. - A broader sweep across recent official launch posts still matters.
Introducing GPT-5.5(April 23, 2026) changes the top-line model recommendation,Codex now offers pay-as-you-go pricing for teams(April 2, 2026) reinforces the Business/Enterprise Codex-only seat path and token billing rollout, andCodex for (almost) everything(April 16, 2026) continues to expand the app story with background computer use, more plugins, multiple terminal tabs, SSH devbox support, and richer artifact/sidebar workflows. - The guide itself also changed structurally today. The intro now includes localized onboarding visuals, the Codex App screenshots were refreshed to April 23, 2026 captures, section 19 (the tool-comparison chapter) was removed, and
computer useis now explained as a standalone feature chapter inside the App section instead of only being mentioned as a model-side capability. - The setup story is clearer than older revisions: Quickstart treats the app as the easiest starting path, the IDE surface explicitly covers VS Code, Cursor, Windsurf, and JetBrains, and API-key sign-in is still allowed but can limit features such as cloud threads and some credits-based functionality.
- Windows guidance is now split more cleanly between the general Windows page and the dedicated Windows app page. The default recommendation is the native app, installable from Microsoft Store or
winget, withelevatedsandbox preferred overunelevated, a private desktop on by default, and WSL2 positioned as the right option when your workflow already lives in Linux or the IDE agent path needs it. - The Codex app docs are broader than a simple desktop shell. The current app, app/features, and app/automations pages emphasize built-in worktrees, Automations, thread-vs-standalone automation choices, Git tools, integrated terminal, voice dictation, pop-out windows, IDE sync, image input, chats, artifact preview, cached web search by default for local tasks, notifications, and sleep prevention. The latest April update also brings background computer use, more plugin coverage, multiple terminal tabs, SSH devbox support, and a richer summary pane into the core app story. Pricing still matters here too: built-in image generation uses general Codex limits and tends to consume them 3-5x faster, while Fast mode doubles credit consumption where it applies.
- Plugins and skills are now documented as a tighter pair. The official
Pluginspage defines plugins as bundles of skills, app integrations, and MCP servers, while theSkillspage makes the progressive-disclosure loading model much more explicit and clarifies that plugins are the installable distribution unit. - Docs MCP remains one of the highest-leverage setup steps. The current guide at
developers.openai.com/learn/docs-mcpstill uses the server URLhttps://developers.openai.com/mcp, confirms that CLI and IDE configuration are shared, and recommends adding an AGENTS.md steering line so Codex consults the docs server automatically for OpenAI-related questions. config.tomlis still the area most likely to drift. The current reference gives more weight toreview_model, top-levelweb_search,tools.web_search,personality,service_tier,default_permissions,tools.view_image,windows.sandbox,windows.sandbox_private_desktop,model_instructions_file,memories.disable_on_external_context, granular approvals, app permissions, feature flags, and named permission profiles.- A wider sweep across
developers.openai.com/codexandopenai.com/indexstill did not justify a new top-level chapter today, but it did confirm that the guide should keep App-first onboarding, Docs MCP grounding, and model-selection guidance at the top while using Codex for OSS, the AI-native engineering team guide, and launch posts as supporting references. The OSS page is now especially worth noting because it highlights six months of ChatGPT Pro with Codex plus conditional Codex Security access for eligible maintainers.
- First-time users (10 minutes): install/sign in (
04-06) → keep default sandbox/approval (10) → run one small edit task with Git checkpoint. - Professional users (team rollout): lock AGENTS.md +
.codex/config.toml(12-14) → standardizecodex exec/review flow (15-16) → adopt section17prompt contract as team baseline.
| Section | Topic |
|---|---|
| Start Here | Fast paths for first-time users and professional workflows |
| 01–03 | Ecosystem overview, product suite, supported models |
| 04–05 | System requirements & pricing, installation & auth |
| 06–09 | CLI, App, IDE Extension, Web usage |
| 10–14 | Approval modes, slash commands, AGENTS.md, config.toml, MCP |
| 15–16 | Session management, CI/CD automation |
| 17 | Prompting Codex agents with embedded contracts, workflows, and playbooks |
| 18 | Advanced techniques |
| 19–20 | FAQ, references |
Currently supports Korean 🇰🇷 and English 🇺🇸.
Toggle languages in real-time via the 🌐 button on the top right of the page.
We welcome translation contributions! Add a new language block in
i18n.js.
The initial draft of this guide was created using AI based on the official OpenAI documentation and community resources, then manually reviewed and verified before publishing.
Despite our review, some typos, mistranslations, or inaccuracies may still remain.If you find any issues or have questions, please open an Issue or submit a PR!
Codex is evolving rapidly — always check the official docs for the latest information.
Open source contributions are welcome! 🎉
- 🐛 Bug fixes — Incorrect info, typos, mistranslations
- 🌐 Translations — Add new language support (add to
i18n.js) - 💡 Tips & workflows — Share useful Codex tips
- 📸 Screenshots — Updated UI screenshots
- 📝 Content — Expand or improve existing sections
# 1. Fork & Clone
git clone https://github.com/<your-username>/codex-101.git
cd codex-101
# 2. Open in browser to verify changes
open index.html
# 3. Submit a PR
git checkout -b fix/my-improvement
git commit -m "Fix: correct outdated information"
git push origin fix/my-improvementcodex-101/
├── index.html # Main page (chapter-map overview + 20 sections)
├── style.css # Styles (dark/light theme + intro/computer-use feature blocks)
├── app.js # Interactions (theme, language, section navigation)
├── i18n.js # Translations (KR/EN)
└── images/ # Refreshed screenshots + localized explainer visuals
This project is open source and available under the MIT License.
Made with ❤️ by @swhan0329
Built with the help of AI — PRs welcome!