A method and system for authenticating application program interface (API) invokers using a common application program interface framework (CAPIF) is provided. The method includes establishing by a CAPIF core function (CCF) a secure Transport Layers Security (TLS) connection with at least one API invoker, on receiving a connection request from the at least one API invoker to access at least one service API on a CAPIF-2e interface. Further, the method includes determining by the CCF at least one security method to be used by the at least one API invoker for a CAPIF-2e interface security (C2eIS) of the at least one API invoker for accessing the at least one service API on a CAPIF-2e interface. The method further includes enabling the C2eIS by an API exposing function (AEF) the at least one API invoker based on the determined at least one security method.