# What Is localhost:3000?

> Your browser uses localhost:3000 to reach an app running on your own computer. Sending that address to someone else does not give them access to your app.

Your browser uses `localhost:3000` to reach an app running on your own computer. Sending that address to someone else does not give them access to your app.

## The address has two parts

**localhost** means this device. The familiar IPv4 address `127.0.0.1` serves the same loopback purpose. On your friend's laptop, localhost points to their laptop.

**3000** is a port number. It tells the computer which listening service should receive the connection. Your development server may use another port, such as 5173 or 8080.

If the browser says it cannot connect, check that the development server is running and use the address printed in its terminal. Closing that process stops the server.

## How to share what you built

For a short demonstration, a tunnel can forward a public URL to your running development server. Your computer and server must stay on. Read [Cloudflare Quick Tunnels](https://developers.cloudflare.com/cloudflare-one/networks/connectors/cloudflare-tunnel/do-more-with-tunnels/trycloudflare/) before exposing a project.

For a website that should remain available when your laptop is off, deploy it to a host. A static HTML project can go to [Netlify](https://docs.netlify.com/deploy/create-deploys/) or [Cloudflare Pages](https://developers.cloudflare.com/pages/get-started/direct-upload/). An app with a database or server process needs hosting for those parts too.

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## Frequently Asked Questions

### Can someone else open my localhost:3000 link?

No. Their browser will look for a server on their own device. Use a hosted deployment or a tunnel to your running server.

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