What Are RPC APIs

RPC stands for remote procedure call and simply refers to calling another function. Unlike REST, which is all about resources (i.e. data), RPC is all about actions, i.e. triggering remote functions.

As a great example, Slack's Web API consists of HTTP RPC-style methods where you call (e.g. POST) an action using a URL in the form of https://slack.com/api/METHOD_FAMILY.method.