The Popcoin API is a service that developers install into their own systems to generate variable usage costs at as micro or macro a level as they desire. It's available in JSON format with access token as the authentication method. Popcoin is a metered billing service for developers.
Sixteen APIs have been added to the ProgrammableWeb directory in categories including Messaging, Mapping, Air Travel, and Customer Service. Highlights include Facebook Messenger Broadcast API, plus APIs from Mobius, Nylas and Apptivo. Here's a rundown of the latest additions.