Website Tag Validator is a program to bypass site verification bots. Simply what happens is, sometimes when filling a form or a aplication for a site it require the user to post a snip of text into his/her website to validate. This code is just to confirm that the site you mention is actually yours. With Website Tag Validator the user just enters the tag in the program and hit add. In the form just point the website bot to https://hacxx.000webhostapp.com/.
Website Tag Validator isn't just a site verification tool, it can include SPA (Single-Page-Applications). Just write your HTML file or copy/paste the code and hit add. Automatically the homepage of https://hacxx.000webhostapp.com/ will change to your site. If it has external elements for example other people codes and tags simply hit the delete button and add the code.