WebFinger
WebFinger is a protocol specified by the Internet Engineering Task Force IETF in RFC 7033 that allows for discovery of information about people and things identified by a URI.[1] Information about a person might be discovered via an acct: URI, for example, which is a URI that looks like an email address.
WebFinger is specified as the discovery protocol for OpenID Connect,[2] which is a protocol that allows one to more easily log in to various sites on the Internet.[3]
The WebFinger protocol is used by federated software, such as GNU social, Diaspora,[4] or Mastodon,[5] to discover users on federated nodes and pods, as well as the remoteStorage protocol.[6]
As a historical note, the name "WebFinger" is derived from the old ARPANET Finger protocol, but it is a very different protocol designed for HTTP.[7]
The protocol payload is represented in JSON format.