With Recurly.js and our Transparent Post, merchants only need to fill out the Self Assessment Questionnaire A.
We launched our own Transparent Post back in March 2011. We created Recurly.js to simplify performing client-side validation, pricing calculations (w/ coupons, VAT, add-ons), and proper error handling when a transaction is declined. It's 10x easier to implement than Transparent Post, and has a much better user experience for the customer.