How can you determine the "system requirements" of a site?

Question

Browsers

I am finishing the site, I used HTML5 and CSS3 with might and main, plus several JS libraries, and so, I cannot manually check from which version of browsers they started supporting the tag/property/API.
Is there some utility that would check the page and the styles and scripts connected to it, and give out the minimum versions of browsers in which everything will work?

Answer 1

The following sites are used for this:
* caniuse.com
* diveintohtml5.info/everything.html
* quirksmode.org/compatibility.html