This is the official Shopify Ruby Gem that allows developers to programmatically access the admin functionality of Shopify stores. Developers can create apps for themselves through their own admin access. All API usage happens through Shopify applications; shop owners can create applications for themselves through their own admin. Developers are given functionality across articles, assets, customers, events and more. The API uses a RESTful interface and responses are formatted in XML and JSON.
Switch announced the CardSavr API which allows credit card details to flow directly from the card issuer to thousands of ecommerce sites. Once integrated, updated card information can be sent to the selected sites without users needing to reload the information, or card issuers to reissue cards.