Developer tool

Localhost URL Builder

Use the homepage builder to combine protocol, host, port, and path into a clean local URL you can copy or open.

Use URL Builder

Fast checklist

  1. 1 Choose http or https.
  2. 2 Choose localhost, 127.0.0.1, 0.0.0.0, or a LAN IP pattern.
  3. 3 Select or type the port your server prints.
  4. 4 Add the path, then copy or open the generated URL.

Quick diagnostic checks

Build the exact local browser URL http://localhost:3000/path

Use this when a tutorial, AI response, or terminal output gives you pieces of a localhost URL that need to be assembled correctly.

Switch host without losing the route localhost -> 127.0.0.1

Keep the same protocol, port, path, and query string when comparing localhost with the numeric loopback address.

Prepare a LAN test URL http://LAN-IP:PORT/

Use this for phone testing only after the dev server is configured to accept network connections.

Live request check

What this page sees

Detecting what the server sees...
Public IP Checking...
Request line Checking...
HTTP request headers
Loading headers...

Sensitive headers such as cookies and authorization tokens are filtered before display.

Why a builder helps

Local URLs are easy to break when a slash, colon, port, or protocol is missing. A builder makes the shape explicit.

When not to use a browser URL

Database ports such as 3306 and 5432 are not normal browser pages. Use the proper database client instead.

What the builder does not verify

The builder creates a valid URL shape. It does not prove that a server is running, that a port is open, or that a framework route exists.

  • Use a port command when you need process ownership.
  • Use the request inspector when you need the browser and request context.
  • Use the troubleshooting guides when the generated URL still fails.

Related localhost guides

Network guide

Access localhost from phone

Learn why localhost on a phone points to the phone itself and how to access a local development server from mobile.

Developer tool

Localhost Port Lookup

Look up common localhost ports, what they are usually used for, and which command can check if a port is busy.

Typo guide

Localhost Typo Fixer

Fix common localhost typos such as locallhost, localhos, lcoalhost, localhost.com, http localhost, and https localhost.

Port guide

localhost:3000

Open localhost:3000, learn which development servers commonly use port 3000, and fix connection errors quickly.

FAQ

Can I use the builder for phone testing?

Yes. Use your computer LAN IP plus the local port, and make sure the dev server accepts network connections.

Does this tool send my URL anywhere?

No. The builder runs in the browser and does not require an account or external API.

Does this tool make network calls to third-party services?

The URL builder and port lookup run in the browser, and the request inspector uses this same site endpoint. Locallhost.im uses Pageview for basic pageview analytics, but the request inspector does not call a third-party IP lookup API.

Why should I copy the debug snapshot?

The snapshot gives a concise record of the URL, request line, safe headers, user agent, and browser context. It is useful when reporting a localhost issue to a teammate or coding assistant.

Are cookies and authorization headers shown?

No. Sensitive headers such as cookies, authorization, and common API token headers are filtered before display.