Why I'm still using the "Certainly Something" addon for Firefox
My Firefox addons haven't changed recently (they've been the same for a few years now, somewhat to my surprise). This includes my continued use of Certainly Something. What is odd about this is that if you look at the source repository for Certainly Something, it notes that the addon was integrated into Firefox 72 (and the separate version is no longer maintained). I've known about this for a while, but I keep on with Certainly Something installed, and I even keep using it periodically. There are two reasons for this.
The first reason is that Certainly Something gives me the full connection information and the certificate information in one place, in a form that gives me specific TLS-level details for the connection instead of Firefox's more vague description. The second is that Certainly Something provides me immediate and convenient access to this through a button in the URL bar, as compared the the much more indirect path that I have to take in Firefox for the native equivalent. The native version requires clicking the padlock, clicking the 'Connection secure' line for more, then 'More information' which will give me a modal popup, and then finally I can click 'View Certificate' to see just the certificate information; the TLS connection information is (or sometimes was) in the modal popup. If I actually want to know the TLS certificate, Certainly Something gives me much better access to it.
(The native Firefox way is also one errant mouse-mispositioning by one line away from 'Clear cookies and site data', which I do not want at all. I'd rather not go near it just in case.)
I understand why Firefox's normal interface is like this, more or less. It's partly because Certainly Something's better TLS certificate viewer was wedged into Firefox's historical interface for this (everything before 'View Certificate' is very old fashioned), and it's partly because this is not considered a high usage or important part of the UI. Normal people don't normally go looking at TLS certificate information (and if they do, arguably someone has failed them). However I'm a system administrator, not a normal person, so sometimes I do care. Those times are why I have Certainly Something around.
I could live without Certainly Something, and someday I may have to (if it stops providing comprehensive information or otherwise quietly starts breaking down). But I'd rather not, so it lives on in my URL bar until then. The built in certificate viewer page exists as an 'about:certificate' page (with a '?cert=...' parameter), so maybe one could have a bookmarklet that invoked it for the current website.
(Or possibly there is a way to have Firefox put a button in the URL bar itself. I still wouldn't replace Certainly Something until I had to because of how it also gives me the TLS connection parameters.)