Grape vs Rails API: What are the differences?

Developers describe Grape as "An opinionated micro-framework for creating REST-like APIs in Ruby". Grape is a REST-like API micro-framework for Ruby. It's designed to run on Rack or complement existing web application frameworks such as Rails and Sinatra by providing a simple DSL to easily develop RESTful APIs. It has built-in support for common conventions, including multiple formats, subdomain/prefix restriction, content negotiation, versioning and much more. On the other hand, Rails API is detailed as "Rails for API only applications". Rails::API is a subset of a normal Rails application, created for applications that don't require all functionality that a complete Rails application provides. It is a bit more lightweight, and consequently a bit faster than a normal Rails application. The main example for its usage is in API applications only, where you usually don't need the entire Rails middleware stack nor template generation.

Grape and Rails API can be categorized as "Microframeworks (Backend)" tools.

"Well documented" is the primary reason why developers consider Grape over the competitors, whereas "Great for quick decoupled apps" was stated as the key factor in picking Rails API.

Grape and Rails API are both open source tools. Grape with 8.87K GitHub stars and 1.09K forks on GitHub appears to be more popular than Rails API with 5.26K GitHub stars and 293 GitHub forks.