ContentfulRails gem helps integrating Contentful with a Rails app. Here is what ContentfulRails does:

• Registers all your models so you get the right classes returned when calling them. (You need to do this manually without ContentfulRails).
• Provides a mountable Rails Engine to receive webhook calls from Contentful when your content changes
• Caches timestamps for Contentful content, so you can use normal ‘Russian Doll’ caching techniques without incurring heavy page load penalties.
• Provides a view helper to parse Markdown