API is undergoing testing. As of right now there is the Javascript API where you include a the javascript file and then execute the functions accordingly on your website.
For those who want to test it out, you basically include this code
<script type="text/javascript" src="http://cheaperinbitcoins.com/theme/default/js/api.js"></script>
and then call the various functions on your links. For instance if you are a merchant and you added a product to the
cheaper in bitcoins.com store, and that product id was
5 then you would create a link like this
<a href="javascript:void(0);" onMouseUp="cib_addToCart(5, 1);">Add to cart</a>
Documentation on this function:
cib_addToCart(product_id, quantity);
Product Id: The #id number of the product you'd like the customer to add to their cart, when upon clicking the link
Quantity: Quantity