Review for Saved Password Editor by Nigel H
Rated 5 out of 5 stars
This addon is a lifesaver. Simply a 5 star addon.
Unfortunately it appears that Mozilla have not created the APIs needed to support this addon with Firefox 57 and later.
Workaround is to change to using the ESR channel that will allow this addon to be used until late June 2018. Hopefully by then one can move back to the main Firefox channel when the required API etc is provided
To create your own collections, you must have a Mozilla Add-ons account.