I work for LoopBack. The purpose of LoopBack is to help you develop and consume APIs. Here is a list of differentiating features:
1. A lot of connectors to backend systems, including an ORM for most of the popular databases, REST/SOAP apis, and other services such as storage and push notification. We want to make the integrations simpler for API developers.
2. Metadata based REST API programming. Write your business functions in plain JS and we'll expose them as REST APIs.
3. Swagger based API explorer that let you see and invoke APIs as you develop them.
4. Built-in user management, declarative ACLs and oAuth 2.0 provider to secure your APIs
5. Client SDKs (JS, Angular, iOS, Android) to help you consume APIs.
6. Strong tooling, including Yeoman based CLI tools and Web based StrongLoop Arc.
https://github.com/strongloop/loopback-sdk-xamarin https://github.com/strongloop/loopback