I didn't know this, but Google hosts a solid, free, and open-source library of fonts:

https://fonts.google.com/

I'm not a fan of Google when it comes to #privacy or #security but - in this case - you do NOT need a #Google account to view, search, or download these awesome #fonts 

Ditto for FontSpace & FontM:

http://www.fontspace.com/
https://fontm.com/