AppScout has a good article on the new Amazon’s payment service:
Amazon on Tuesday unveiled two new payment options that allow Web site owners to shift payment transactions to the online retailer.
With Checkout by Amazon, webmasters will get help from Amazon in managing shipping charges, sales tax, promotions, and post-sale activities including shipments, refunds, cancellations, and charge backs.
Amazon Simple Pay, meanwhile, is a less complicated option for those who don't need Amazon's end-to-end checkout pipeline and order management capabilities.
To enable Checkout by Amazon, webmasters must add Amazon 1-Click to their Amazon.com account and insert a few lines of code into their Web site template. When customers go to check out of the site, they click the "Checkout with Amazon" button, a widget pops up asking for a shipping address, and customers buy via Amazon's 1-Click. Amazon sends them a confirmation e-mail, and users remain on your site.
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