How to add a custom domain name on your localhost using XAMPP. Codes are based on Windows, but Step 2 onward are pretty much applicable on other operating system.

set-custom-domain-on-localhost-with-xampp

Step 1:
Go to: C:\Windows\System32\Drivers\etc\hosts
And add this to the bottom of the file:

=============
127.0.0.1     your.domain.com
=============

Step 2:
Go to [your XAMPP directory]/apache/conf/httpd-xampp.conf

Step 3:
Go to the bottom of the file and copy & paste this code:

=============
<VirtualHost *:80>
   DocumentRoot "[PATH TO YOUR CUSTOM FOLDER]"
   ServerName your.domain.com
   
   <Directory "[PATH TO YOUR CUSTOM FOLDER]">
     Options Indexes FollowSymLinks Includes ExecCGI
      AllowOverride All
      Require all granted
	</Directory>

</VirtualHost>
=============

* Replace [PATH TO YOUR CUSTOM FOLDER] to the folder where your files are located.
  Ex: C:/my/www/folder/
* your.domain.com must be the same on Step 1 & Step 3


Step 4:
Stop Apache on XAMPP, wait for 5 seconds, then click "Start" to start again your Apache.


If all things go well, you can go to your browser, type your.domain.com 
and it will now happily point to your custom local folder.

=======================================
Working example for testsite.com
<VirtualHost *:80>
   DocumentRoot "c:/xampp/htdocs/testsite"
   ServerName testsite.com
   
   <Directory "c:/xampp/htdocs/testsite">
     Options Indexes FollowSymLinks Includes ExecCGI
      AllowOverride All
      Require all granted
	</Directory>

</VirtualHost>
=======================================

testsite is folder at  c:\xampp\htdocs\testsite