Ask HN: How does Intercom and other web apps auto populate user images?

[gvinter]

Many web apps these days have access to some external data feed where they can check an email address against the feed and see if they can find a headshot for that person. What API are they all using?

Examples I've seen so far include Intercom and AgileCRM.

EDIT:

I'm going to assume that they all just use the Gravatar API.