The Rails Email Preview (REP) is a Rails engine that allows users to preview and edit emails in the browser. It is compatible with Rails 4.2+ and comes with two themes: a standalone theme and a theme that uses Bootstrap 3. REP supports features such as sending emails, editing emails, CSS inlining, and internationalization.
Ruby on Rails, often referred to as Rails, is an open-source web application framework written in Ruby. Known for its convention over configuration and don't repeat yourself (DRY) principles, Rails simplifies and accelerates the development of database-backed web applications.