This could also be a bookmarklet. That would make it more secure as bookmarklets only have access to the page you use them on. Looking at the code, you can ind

This could also be a bookmarklet. That would make it more secure as bookmarklets only have access to the page you use them on. Looking at the code, you can indeed run it as a bookmarklet. I went to https://www.example.com https://www.example.com and typed this in the browser console: s1=document.createElement('script'); s1.src='https://code.jquery.com/jquery-3.7.0.slim.min.js'; document.head.appendChild(s1); s2=document.createElement('script'); s2.onload=()=>window.cssProReady(); s2.src='https://csspro.com/demo-build/mainnewnew.js'; document.head.appendChild(s2); Boom! The tool is running. So prefixing that line with "javascript:" and putting it into a bookmark would let you use it on any site you wish, simply by clicking the bookmark. Without having to install an extension. Would be a good alternative the author could offer imho.