Summary  
This chapter explains how to start a local development server with a single command to compile and preview your code, automatically detect and fix startup errors, and interact with the running application in real time.

General domain of usage  
Web application development

Before you can see your app, it needs to be started. This chapter covers that one step and what to do if something goes wrong.

### What running locally means

When Claude Code runs your project it creates a local server on your computer. This uses your Wi-Fi connection to make the app accessible in your browser at an address like `localhost:3000`.

This is not live on the internet. If you send that link to someone else they will not be able to open it. It is only for testing on your own machine.


Note

Think of it like a dress rehearsal. The show is not open to the public yet but everything runs as if it were.

### The command you need to know

This is the command that starts your app. Claude Code will run it for you. When prompted, click Allow.

```
npm run dev
``` 

If the app does not start first time that is normal. Claude Code will read the error and fix it automatically.

### What you should see

When the app loads in your browser for the first time you will see the landing page. You can interact with it and click around. The AI functionality will not work yet because we have not set up the API key. That is what the next chapter covers.

Build and launch a real app in just one weekend using modern AI tools and a simple, practical workflow, using Claude Code to plan, generate, and refine your code, managing your project with GitHub, and deploying your finished app online with Vercel. You’ll start with an idea and quickly turn it into a clear project plan, then move step by step into building a working application, focusing on core features, simple architecture, and fast iteration instead of unnecessary complexity, while learning how to work effectively with AI by writing better prompts, fixing errors, and improving features, ending with a live app, a clean GitHub project, and a repeatable system for turning future ideas into real products faster.

Understand the basics of AI-assisted development, set up your environment, and get familiar with Claude Code before starting your first app.

Turn your idea into a clear, simple plan and define the smallest version of your app that delivers real value.

Go from zero to a running app by generating code with AI, setting up the project, and understanding what was created.

Improve your app by adding features, refining the design, and learning how to fix issues effectively.

Publish your project, make it accessible online, and ensure everything works using GitHub and Vercel.

Running the App Locally

What running locally means

The command you need to know

What you should see