Addon recommendation: 404 Bookmarks

I hope you have bookmark collections.

Bookmarks are efficient, save energy, and are more private, than using "Google" for everything all the time.

But my collections over time include tons of websites that are down!

This is quite sad, but at least using that addon you can filter out those websites.

Or you could search for the link on archive.org, archive.is or other archiving websites.