What I have always loved about the original spec is (https://tools.ietf.org/html/rfc2616 https://tools.ietf.org/html/rfc2616): 10.4.3 402 Payment Required

What I have always loved about the original spec is (https://tools.ietf.org/html/rfc2616 https://tools.ietf.org/html/rfc2616): 10.4.3 402 Payment Required This code is reserved for future use. Reminds that you that the idea, and the problem, of accepting payments on the web was right there at the start. cf. Andreessen: "We should have built payments in the browser."(http://mashable.com/2012/05/01/marc-andreessen-browser-payments/ http://mashable.com/2012/05/01/marc-andreessen-browser-payme...)