Looking for before/after screenshot tools

I don’t care if it’s a backend tool, PHP or JS, or even a 3rd party web service. I’m trying to find a way to record snapshots of web pages for the purpose of archiving or before/after updates or other changes to WordPress websites.

Most often when I do updates, I’ll just open a few pages to make sure the site works before the update, then I’ll do the updates, clear any caches, and check the pages again.
Of course, I didn’t memorize exactly what the pages looked like, I can only verify they still open and don’t crash.

What I’m looking for is a tool that can take real full page screenshots and compare to screenshots taken later after the updates. But not only that, I’d like the screenshots as a way to deal with clients when they come to me and say things like “that one box that used to be in that one place isn’t there any more!”
I have no idea what one box they mean or what it looked like, because nobody has screenshots, I’m trying to re-create something or find out what was there based on verbal descriptions. I could have been a plugin that went defunct or someone removed a widget from a sidebar or anything.

So taking screenshots for “before/after” compare is very handy, but also if I grab a screenshot every week and archive it, I could have something to reference if they ever talk about some feature that disappeared or what have you.

Screenshot tools are difficult because sites run on JS these days, there is scroll jacking and lazy loading and ajax stuff, so making sure the whole actual page is really loaded before the screenshot, is important.

Any ideas about something like this? Especially if it can be scaled to the level of a web maintenance company where it can be used across dozens of sites regularly.

Thanks

Also in #PHP _↴