There's a lot of open issues
A long-lived project that still receives updates
Offsite Payments is a simple 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 put as simple an abstraction as possible on top of offsite (often called hosted) payment pages, and allow contributors to easily help services such as Shopify extend the number of offsite payment services they support.