Abstract: Embodiments provide methods, and server systems for facilitating payment transactions using unique strings. In an embodiment, the method includes receiving, by a server system associated with a payment network, a payment transaction request comprising at least a payment string uniquely associated with the payment card linked with the issuer account and a transaction amount to be paid to the merchant. The method includes verifying a validity of the payment string based on at least one rule set. The method includes retrieving issuer account information associated with the issuer account based on at least a part of the payment string upon successful validation of the payment string. The method includes facilitating the payment transaction based at least on the retrieved issuer account information from the issuer account to the acquirer account.