Skip to content


Switch branches/tags

Name already in use

A tag already exists with the provided branch name. Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. Are you sure you want to create this branch?

Latest commit


Git stats


Failed to load latest commit information.
Latest commit message
Commit time


πŸ”— Run your dev servers on addresses like https://awesome-site/ or https://πŸ”/1 instead of ugly addresses like http://localhost:1337

localhost-mapper Example

You can run your localhost servers on practically any address like:
http://πŸŽπŸ¦„.πŸ‘©β€πŸ’»/1 (HTTPS will automatically be supported even if your original server listens only on HTTP)

Works on macOS and Windows, and Linux with some manual config.


$ yarn add --dev localhost-mapper


$ npm i --dev localhost-mapper


Import the module and use it like:

import lhMapper from 'localhost-mapper'
// or const lhMapper = require('localhost-mapper')

// [...] your server code here [...]

const { PORT = 31415 } = process.env`http://localhost:${PORT}`, 'http://awesome-site')
  .then(() => console.log('listening on http://awesome-site'))

// now open http://awesome-site in a browser

or type in the following in a terminal:

$ lh-map http://localhost:31415 http://awesome-site

How It Works

localhost-mapper works by creating a Proxy Auto-Config (PAC) file and automatically changing the PAC URL setting on Windows and macOS. The original setting is restored when localhost-mapper isn't being used.

It's incompatible with cURL and Wget since they don't support PAC files. Also, automatic changing of the PAC URL hasn't been implemented for Linux, so you'll have to manually set the PAC URL for your browser or OS.

Why not simply edit the /etc/hosts file?

The hosts file cannot map to different ports. So you can map http://localhost:1337 β†’ http://unicorns:1337 easily but not http://localhost:1337 β†’ http://unicorns without listening on port 80. Listening on port 80 requires sudo.

Since you can only get one server to listen on port 80, the hosts file is limited to just a single mapping. With localhost-mapper, you can map as many hosts as you want simultaneously (http://localhost:31415 β†’ https://alice, http://localhost:1234 β†’ http://bob).

Manually editing the hosts file is a lot of work, compared to localhost-mapper which can be used by just adding a line of code that you can forget about. localhost-mapper will only be active when you run code that imports it. It'll restore all filesystem/network changes when it's not being used.

When you share your code, other people will have to manually edit the hosts file on their environment, but with localhost-mapper they can start using the prettified domain out of the box as soon as they run the code.

API String, newAddress: String|Array<String>|RegExp, [options: Object]): Promise<void>

Forwards originalAddress to newAddress (http://localhost:1337 β†’ http://cat.meow). Aliased as localhostMapper.add.

originalAddress: String

The original address to be proxied/forwarded to newAddress. Like http://localhost:1337.

newAddress: String|Array<String>|RegExp

The new address to listen on. Like http://awesome-site. Pass in an array of strings to listen on multiple addresses in one call. Also supports regex, like /http\:\/\/.*everything\.awesome/

If this starts with https:, self-signed certificates will be generated and a HTTPS server will be created that proxies originalAddress. So HTTPS will work even if originalAddress listens only on HTTP. To use your own certs, check out the ssl option below. If you pass in a RegExp that matches HTTPS domains, you must set ssl to true to use automatically generate and use self-signed certificates.

options: Object
  proxy: Boolean,
  proxyConfig: Object,
  ssl: {
    key: String,
    cert: String
proxy: Boolean

By default, localhost-mapper proxies the contents of originalAddress so that the Host header is unchanged. This makes sure it is compatible with codebases that it wouldn't otherwise be without requiring changes. Setting this to false will disable proxying.

proxyConfig: Object

Passed as-is to http-proxy. Only applicable when proxy is not false.

ssl: { key: String, cert: String }

Contents of key/cert file to use for HTTPS. Set this to true to automatically generate and use self-signed certificates.

localhostMapper.unmap(newAddress: String|Array<String>|RegExp): Promise<void>

Undos the call, i.e. stops listening for newAddress. All addresses will automatically be removed when the node process exits. Aliased as localhostMapper.remove.

[1]: While all browsers support emoji domains, not all show the actual emoji in the address bar. Safari will show the emoji like you'd want it to, while Chrome and Firefox will show the Punycode version: http://xn--ui8h/


  • winproxy for the executable to change PAC URL automatically in Windows (licensed under Apache-2.0)
  • hotel for the inspiration


MIT Β© Kishan Bagaria


πŸ”— Run your dev servers on addresses like https://awesome-site/ or https://πŸ”/ instead of localhost








No releases published


No packages published