Active Merchant is a simple payment abstraction library used in and sponsored by Shopify. It is written by Tobias Luetke, Cody Fauser, and contributors. The aim of the project is to feel natural to Ruby users and to abstract as many parts as possible away from the user to offer a consistent interface across all supported gateways.
Gem for Rails that lets you specify attributes that will not be loaded when you do a find until you refer to those attributes. Great for speeding up your app if your table has a lot of text/blob columns.