I am also a website developer and I use XAMPP on my PC when developing and testing my client websites, which is perhaps one of the intentions of the XAMPP developers when creating the package.
Your clients, and mine, may well be hosting their websites on a Linux based Apache web server - the only major difference is the OS being used.
It is not intended that XAMPP be used as web server in a production environment ie. as a 'permanently connected to the Internet' web server on a local PC - some security issues that are not addressed in a default installation can be disastrous.
The XAMPP website wrote:The license
XAMPP is a compilation of free software (comparable to a Linux distribution), it's free of charge and it's free to copy under the terms of the GNU General Public License. But it is only the compilation of XAMPP that is published under GPL. Please check every single license of the contained products to get an overview of what is, and what isn't, allowed.
In the case of commercial use please take a look at the product licenses (especially MySQL), from the XAMPP point of view commercial use is also free.
The license and more on the XAMPP home page:
http://www.apachefriends.org/en/xampp.htmlBy the way, you can make a helpful donation for it's use if you feel it would help compensate for it's commercial use, which would be received with thanks and greatly appreciated - details at the top of the above home page.