Amazing. I can't believe this ancient extension doesn't have more users! Very simple; it uses the regular Firefox search site list (with the option to ignore some). I used other context search extensions for years, but this one is the best.

Installed, and listed under Add ons however, there is no option in the search bar for Advanced search, nor any icon for it in the Add on toolbar in my FF 119.
Sorry. Yet this could be helpful since Google,etc. no longer regards minus -exclusions in searches.

All that's missing is the option to open searches in the background, and maybe the option to nest engines into folders (since I can also hide engines from the context menu without hiding them from the address bar).

Finally !! simple, easy, light, non intrusive, and lets me choose what search engines i want to display in context menu. only been using for a few days but so far no bugs or issues.

PERFECTO !!

Custom Search with just 2 clicks! Perfect for translations, wiki lookups.
Should have been a feature of Firefox!
Search bar usage: decreased by 70%

Simple to use. I like how it matches with default Firefox style.