Case Study

Building a Full-Stack App with Claude Code: A Step-by-Step Walkthrough

From zero to deployed in one session. See how Claude Code transforms building a complete task management application with React, Node.js, and PostgreSQL.

The Goal: Build a Task Manager in One Session

We're going to build TaskFlow - a complete task management application with user authentication, real-time updates, and a clean UI. This isn't a toy project. It's a production-ready app with proper architecture, error handling, and deployment configuration.

The goal isn't to show that Claude Code writes perfect code. It's to show how AI-assisted development changes your workflow - from explaining requirements to having working software.

What We're Building

  • • Frontend - React with TypeScript, Tailwind CSS, real-time WebSocket updates
  • • Backend - Node.js/Express API with JWT authentication
  • • Database - PostgreSQL with proper migrations
  • • Features - Task CRUD, drag-and-drop ordering, due dates, labels, search

Phase 1: Project Setup

Start by telling Claude what you want to build. Be specific about your tech stack preferences - Claude will work with whatever you prefer.

# Initial prompt to Claude

"I want to build a task management app called TaskFlow.

Stack: React + TypeScript frontend, Node.js + Express backend,

PostgreSQL database. I want user authentication with JWT,

real-time updates via WebSockets, and a clean modern UI.

Start by setting up the project structure and basic boilerplate."

Claude creates the complete project structure: separate frontend and backend directories, TypeScript configuration, ESLint setup, and a Docker Compose file for local PostgreSQL. It doesn't just scaffold - it creates a working foundation with proper patterns already in place.

Phase 2: Database and API

With the structure in place, move to the data layer. Describe your domain model and let Claude implement the schema and API endpoints.

// What Claude generates for the database schema

CREATE TABLE users (

id UUID PRIMARY KEY DEFAULT gen_random_uuid(),

email VARCHAR(255) UNIQUE NOT NULL,

password_hash VARCHAR(255) NOT NULL,

created_at TIMESTAMPTZ DEFAULT NOW()

);


CREATE TABLE tasks (

id UUID PRIMARY KEY DEFAULT gen_random_uuid(),

user_id UUID REFERENCES users(id) ON DELETE CASCADE,

title VARCHAR(255) NOT NULL,

description TEXT,

status VARCHAR(50) DEFAULT 'todo',

due_date TIMESTAMPTZ,

position INTEGER NOT NULL,

created_at TIMESTAMPTZ DEFAULT NOW()

);

Claude also creates the migration system, seed data for testing, and complete CRUD API endpoints with proper validation, error handling, and TypeScript types. Each endpoint follows RESTful conventions and includes authentication middleware.

Phase 3: Authentication Flow

Authentication is where many tutorials cut corners. With Claude, you get a complete implementation: secure password hashing, JWT token management, refresh token rotation, and protected route middleware.

# Tell Claude what you need

"Add JWT authentication with refresh tokens.

Access tokens expire in 15 minutes, refresh tokens in 7 days.

Store refresh tokens in the database so we can revoke them.

Add login, register, logout, and refresh endpoints."

Claude implements the full flow: bcrypt for password hashing, secure HTTP-only cookies for tokens, CSRF protection, and a React context provider that automatically handles token refresh before expiration.

Phase 4: Building the UI

Now the fun part. Describe the UI you want and watch Claude build it component by component.

# UI requirements

"Build the main task board UI:

- Three columns: Todo, In Progress, Done

- Drag and drop between columns

- Click to expand task details

- Quick add at top of each column

- Search bar that filters in real-time

Use @dnd-kit for drag and drop."

Claude creates reusable components: TaskCard, TaskColumn, TaskModal, SearchBar. It handles all the drag-and-drop complexity, optimistic updates for responsiveness, and syncs position changes to the backend.

Phase 5: Real-Time Updates

Adding WebSocket support lets multiple users see changes instantly. Claude sets up Socket.io on the backend and hooks it into the React state management.

// Claude's WebSocket implementation

// Backend: Emit events when tasks change

io.to(userId).emit('task:updated', { task });


// Frontend: React hook for real-time sync

const

useTaskSync = () => {

useEffect(() => {

socket.on('task:updated', handleTaskUpdate);

socket.on('task:created', handleTaskCreate);

socket.on('task:deleted', handleTaskDelete);

}, []);

};

Phase 6: Testing and Polish

Before deployment, Claude helps write tests and fix edge cases. Ask it to review the code for potential issues - it often catches things you'd miss.

# Testing prompt

"Review the codebase for security issues, add input

validation where missing, and write integration tests

for the auth flow and main task operations."

Claude identifies missing validation, adds rate limiting to prevent abuse, and creates a comprehensive test suite. It also suggests improvements like adding indexes for common queries and implementing request logging.

Phase 7: Deployment

Finally, get it running in production. Claude generates Dockerfiles, environment configuration, and deployment scripts for your platform of choice.

# Deployment setup

"Create Docker configuration for production deployment.

I'll deploy to Railway. Include:

- Multi-stage Dockerfile for smaller images

- Environment variable configuration

- Database migration script that runs on startup

- Health check endpoint"

What This Approach Enables

Rapid Iteration

Change direction instantly. Don't like the UI approach? Describe a different one. Want to swap databases? Claude refactors the data layer. The cost of experimentation drops dramatically.

Learning by Doing

See best practices in action. Every piece of code Claude generates is an opportunity to learn patterns, libraries, and techniques you might not have encountered.

Focus on What Matters

Spend mental energy on product decisions, not boilerplate. When authentication takes 5 minutes instead of a day, you can focus on what makes your app unique.

Consistent Quality

Claude maintains consistent patterns throughout the codebase. No stylistic drift, no forgotten error handlers, no inconsistent naming.

Tips for Full-Stack Projects with Claude

  • Start with structure - Get the project skeleton right before diving into features
  • Work in layers - Database → API → UI. Each layer builds on the previous
  • Be specific about preferences - If you want Tailwind over styled-components, say so
  • Review as you go - Don't wait until the end to understand what was built
  • Test early - Catch issues before they compound across the codebase
  • Use version control - Commit frequently so you can revert experiments that don't work

The Results

In a single extended session, we built a complete task management application with features that would traditionally take days or weeks. The code is production-quality, well-tested, and follows modern best practices.

This isn't about replacing developers - it's about amplifying them. You still need to understand what you're building, make architectural decisions, and review the output. But the mechanical work of typing out boilerplate, looking up API docs, and debugging syntax errors largely disappears.

The question isn't whether AI can help build software. It's how to integrate it into your workflow effectively. Start with a real project, stay engaged with the process, and iterate based on what works for you.