It's invaluable when you want to prototype or verify something from "production" without access to the backend and dev tools are "not enough": 1) save HTML of a

It's invaluable when you want to prototype or verify something from "production" without access to the backend and dev tools are "not enough": 1) save HTML of any page (you know, view-source:URL, ctrl+s), 2) put <base href="URL"> there, 3) open it from localhost or even as a file:///, 4) if you want to make changes to say CSS, again save the original and (absolutely) link your local duplicate. You have to rewrite url()s there, though: sadly, there is no @base for CSS. Saved me some time of waiting for credentials or slow preview from backend.