To use the Razorpay Card Payment Service please contact Razorpay support to enable the S2S JSON API functionality. Information on this API can be found here
Razorpay requires the browser_info field and the following buyer fields: buyer.email_address, buyer.first_name, buyer.last_name, buyer.phone_number. Razorpay also requires an IP Address to be passed for the customer, see here for more information on sending IP Addresses.