I was having a read through some source code on a project and came across a reference to Avatars.io, which is a pretty nice service for fetching avatars.
I'll be using this in future for something like Gravatar rather than having to hash an email and generate a link. For example I can do
https://firstname.lastname@example.org. If I wanted my Twitter avatar then it's
https://avatars.io/twitter/tj_fogarty. It also supports Instagram, and Facebook.
Check out Avatars.io