How to Build and Deploy an App in One Day with AI

You can build and deploy a working app in a single day. Not a mockup. Not a wireframe. A real, functional application that lives on the internet and does something useful.

I have watched people do it in under six hours, and the ones who pull it off are not necessarily better programmers—they just use AI coding agents instead of writing every line by hand.

Here is the short version of how it works: You describe what you want. An AI agent scaffolds the entire codebase. You iterate through a handful of refinement loops. You deploy. You go to dinner with a live URL in your pocket.

The key steps look like this:

1. Spend 30 minutes on setup and spec writing.
2. Use an AI coding agent to generate your full scaffold in about an hour.
3. Run 3-5 iterative coding loops to build features, fix bugs, and polish.
4. Test locally for 30 minutes.
5. Deploy in 15 minutes.
6. Share it with the world.

Total time: 4-8 hours depending on complexity and experience.

Let me walk you through exactly how to do it.

Why This Works Now

The reason you can build an app in a day is not because the frameworks got easier-although they did. It is because AI coding agents have crossed a threshold where they can hold context across an entire project, generate working code across multiple files, and handle the boring infrastructure stuff that used to eat half your weekend.

We are not talking about autocomplete. We are talking about agents that take a specification, plan an architecture, write frontend and backend code, create database schemas, write tests, and generate deployment configurations.

The human job shifts from write code to review code and steer direction.

Two tools make this workflow especially smooth: Coding Agent Loops and Felix, both available on Claw Mart.

Coding Agent Loops gives you 50+ reusable prompt templates and session scripts designed for iterative app building with LLMs like Claude 3.5 Sonnet or GPT-4o.

Felix is a pre-configured AI coding agent built on Anthropic Claude that handles full-stack development-code generation, debugging, deployment scripts-right inside VS Code.

Step 0: Write a One-Page Spec (30 Minutes)

Before you touch any tool, write down what you are building. One page. Not a product requirements document-just a clear description that an AI can work with.

Here is what to include:

• What the app does in one sentence.
• Core features - list 3 to 5, maximum.
• Tech stack preferences if you have them. If you do not, default to Next.js + Supabase + Vercel.
• Any API integrations.

This spec is your anchor. Every time the AI tries to add features you did not ask for, you point back to this document.

Step 1: Set Up Your Environment (30 Minutes)

You need a few things installed and configured before you start generating code.

Software: VS Code, Node.js, Git.

Accounts: GitHub, Vercel, Supabase, Anthropic API key.

Tools from Claw Mart: Download Coding Agent Loops and Felix.

One critical note: disable GitHub Copilot before running Felix. They conflict with each other. Once Felix is installed, authenticate with your Anthropic API key through the extension settings.

Step 2: Scaffold with Felix (1 Hour)

Open VS Code, create a new project folder, and talk to Felix. The command looks something like this:

@felix init recipe-finder --stack=nextjs-supabase-openai

Felix will generate your entire project scaffold in about five minutes:

• Next.js app structure
• Supabase client setup
• API routes
• Database schema
• Environment variables

Every file you need to start.

Review what Felix generated. Then commit to Git. This is your baseline.

Step 3: Build Features with Iterative Loops (3-5 Hours)

This is where the real work happens. You are going to run a series of coding loops.

Each loop follows the same pattern:

1. Tell Felix what to build.
2. Felix generates code.
3. You review the code.
4. You test locally.
5. You either accept or iterate.

Start with your most important feature. Give Felix a clear prompt: build a search page with an ingredient input field, create an API endpoint that queries Supabase for recipes matching those ingredients, display results in a card grid.

Felix will write the frontend code, the backend API, and the database query.

Test it. If yes, move to the next feature. If no, tell Felix what broke and ask it to fix.

Repeat until your core features are working.

Step 4: Test Locally (30 Minutes)

Before you deploy, test everything locally. Check every feature you built. Click around. Try edge cases.

What happens if the user enters no ingredients? What happens if the API times out?

Fix what you can.

Step 5: Deploy (15 Minutes)

Push to GitHub, connect to Vercel, deploy.

Vercel will automatically detect your Next.js app and deploy it.

Once deployed, test in production. Sometimes things break in production that worked locally.

If something breaks, fix it and push again.

Step 6: Share It

Send the URL to someone. Anyone. Get feedback. That is how you validate whether what you built is useful.

Common Mistakes

1. No spec: You cannot prompt your way to a complex app. Write the spec first.

2. Too many features: Start with three. Ship. Then add more.

3. No review: The agent writes code. You review it. That is the workflow.

4. Perfectionism: Ship it. It is an MVP. You can always iterate.

What to Do Next

1. Pick your app idea today.
2. Write your one-page spec tonight.
3. Get Felix and Coding Agent Loops from Claw Mart.
4. Block out your build day.
5. Follow the phases above.

Go build something.