webapp2 vs. Trailblazer vs. Spring

webapp2 is a simple. it follows the simplicity of webapp, but improves it in some ways: it adds better URI routing and exception handling, a full featured response object and a more flexible dispatching mechanism.

Trailblazer is a thin layer on top of Rails. It gently enforces encapsulation, an intuitive code structure and gives you an object-oriented architecture. In a nutshell: Trailblazer makes you write logicless models that purely act as data objects, don't contain callbacks, nested attributes, validations or domain logic. It removes bulky controllers and strong_parameters by supplying additional layers to hold that code and completely replaces helpers.

A key element of Spring is infrastructural support at the application level: Spring focuses on the "plumbing" of enterprise applications so that teams can focus on application-level business logic, without unnecessary ties to specific deployment environments.