For both browser extensions, follow the instructions they provide.
Search Facebook Without an Account Until a few years ago, you could look up almost every user on Facebook through one method or another.
See if any one if known to you.
Social Searcher is a free Social Media Search Engine that allows you to search for people and content in various social networks.
It will shows ton loads of information.
In the bottom of the sign-up home page, you will find many kinds of options like Languages, Instagram, Friends, Places, Create Ad, Developers etc.