- Entrepreneurs who need to ship a landing page and blog without hiring a developer
- Semi-technical managers who are tired of wrestling with the command line and Git
- Codex users ready to move from single prompts to automated assembly lines
Guides OpenAI
Set Up a Coding Factory With the New Codex App
This guide shows you how to use the Codex app as a “coding factory” for building a website brick by brick.
Introduction
This guide shows you how to use the Codex app as a “coding factory” for building a website brick by brick. Instead of relying on one long vibe-coding session until you run out of tokens, you’ll plan a modular workflow where multiple Codex agents can work on separate parts of a React app in parallel.
You’ll produce a reusable Codex workflow for building a professional SaaS-style website with parallel agents, feature branches, commits, previews, and automations that can keep working day by day.
Think modular and plan for parallel tasks so multiple Codex agents can work without file conflicts.
Step-by-step 7 steps
Instructions
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Step 1 of 7 Create a New React App
Start by scaffolding a new React app.
Run this in your terminal to create a new React app with Vite:
$ npm create vite@latest vite-react-app -- --template react
💡 Pro tip: If you don’t use Vite, you can use Next.js, Create React App, or another React setup instead. If you’re not sure what to use, ask AI to help you choose.
The Codex app runs in a sandbox by default, so creating the project in your terminal first keeps setup simple and helps keep your Codex sidebar tidy later.
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Step 2 of 7 Set Up Codex
Get the Codex app, open it, and sign in.
Click Open Folder, or use Cmd + O / Ctrl + O, and select the folder you just created.
Click “Create git repository” in the bottom right. This helps your agents keep track of what they are working on.
💡 Pro tip: You can log in with GitHub by opening the terminal with Cmd + J / Ctrl + J and running gh auth login. This lets Codex publish code to GitHub for you.
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Step 3 of 7 Create the First Plan
Have Codex make a plan for the app. Click the plus button and toggle on plan mode.
Create a modular PRD (in markdown) and execution plan for a professional boilerplate SaaS website. The project must be built using a "Parallel Factory" workflow where multiple agents can work on separate pages simultaneously without file conflicts. Phase 0: The Designer Agent (Global Infrastructure). Then parallel agents should create components and pages for a landing page, blog, about page, contact us page, pricing page and privacy page. The only agent that can edit the main App.jsx is you.Pro tip: You can see your PRD and other files by clicking Open > Open in, then choosing your IDE.
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Step 4 of 7 Run Phase 0
Create a new thread and tell the agent to get started on Phase 0 of the app. You can tag the PRD file with the @ sign.
💡 Pro tip: Click the commit button in the top right to save an agent’s progress. Commits act like checkpoints that help other agents understand what is going on, and Codex can auto-generate a commit description for you.
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Step 5 of 7 Start the Factory
Start agents for each page. Open a thread for each page mentioned in the PRD and tell each agent to get to work.
💡 Pro tip: Instruct your agents to open new feature branches for each page.
When the page agents are done, have your main “foreman” agent review each feature branch and merge it into your codebase.
You can launch a preview of your website from Codex. Click the play button in the top menu and enter:
npm install
npm run dev
Then preview your app by pressing the play button.
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Step 6 of 7 Add Automations
Click Automations to have agents review your work every hour, day, or on another schedule. You can schedule daily commit reviews, bug hunters, and feature builders.
Instead of vibe coding in a multi-hour sprint and running out of tokens, try dropping in your PRD and turning on automations like:
- Daily feature builder agent that builds the next thing on the PRD
- Commit review agent that checks the feature agent’s code each day
- Bug hunter that looks for bugs each day and fixes them
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Step 7 of 7 Install Useful Skills
Click Skills in the sidebar to install useful tools for Codex in one click.
You're done
That's the whole workflow
Mark it complete to save your progress. Background and answers to common questions follow below.
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Overview Back to the steps
Background and context
Who This Is Useful For
What You Will Build
You will build a team of Codex agents that can work on a React SaaS website in parallel, with a PRD guiding separate agents across shared infrastructure, pages, reviews, and automations.
- A new React app scaffolded with Vite
- A modular PRD and execution plan for a professional boilerplate SaaS website
- Parallel agents for pages such as landing, blog, about, contact, pricing, and privacy
- A main “foreman” agent that can review and merge feature branches
- Optional automations for feature building, commit review, and bug hunting
What You Need
- A Mac computer
- ChatGPT Plus ($20/month) or higher
- The Codex app
- A terminal for scaffolding the initial React app
- Optional: GitHub login through gh auth login if you want Codex to publish code to GitHub
Going Further
- After the core factory is running, you can reuse the PRD with Codex automations to schedule daily feature builders, commit reviewers, and bug hunters. You can also install additional Codex Skills from the sidebar to add useful tools in one click.