What kind of Service is OpenID and Gravatar

Question

The reason I ask is beacause I want to find other services like these two. It saved me alot of time developing my own solution. So what is the name of these kind of services?

Answer 1

I don't know if there's an official term for them, but they're often referred to as web services or lately, Open API services.

Answer 2

There's probably not one exact term that describes what you're looking for. But some related terms would include: web services, APIs, single sign on systems, OAuth, etc. It's simply interoperability and shared open data online.