An application programming interface, API, invoker for performing an onboarding, the API invoker comprising: a transceiver ; and a processor coupled with the transceiver and configured to: obtain, from a service provider via the transceiver , onboarding information including an onboarding credential and information of a common API framework, CAPIF, core function , wherein the onboarding information is used to authenticate an onboarding of the API invoker to the CAPIF core function ; establish a transport layer security, TLS, session with the CAPIF core function using the onboarding information; transmit, to the CAPIF core function via the transceiver , an onboard API invoker request message along with the onboarding credential; and in case that the onboarding credential is successfully validated, receive, from the CAPIF core function via the transceiver , an onboard API invoker response message including a certificate of the API invoker, wherein the onboard API invoker response message includes an assigned API invoker identifier, ID, and authentication and authorization information, and wherein the certificate of the API invoker is generated by the CAPIF core function , after a successful validation of the onboarding credential. a transceiver ; and a processor coupled with the transceiver and configured to: obtain, from a service provider via the transceiver , onboarding information including an onboarding credential and information of a common API framework, CAPIF, core function , wherein the onboarding information is used to authenticate an onboarding of the API invoker to the CAPIF core function ; establish a transport layer security, TLS, session with the CAPIF core function using the onboarding information; transmit, to the CAPIF core function via the transceiver , an onboard API invoker request message along with the onboarding credential; and in case that the onboarding credential is successfully validated, receive, from the CAPIF core function via the transceiver , an onboard API invoker response message including a certificate of the API invoker, wherein the onboard API invoker response message includes an assigned API invoker identifier, ID, and authentication and authorization information, and wherein the certificate of the API invoker is generated by the CAPIF core function , after a successful validation of the onboarding credential. obtain, from a service provider via the transceiver , onboarding information including an onboarding credential and information of a common API framework, CAPIF, core function , wherein the onboarding information is used to authenticate an onboarding of the API invoker to the CAPIF core function ; establish a transport layer security, TLS, session with the CAPIF core function using the onboarding information; transmit, to the CAPIF core function via the transceiver , an onboard API invoker request message along with the onboarding credential; and in case that the onboarding credential is successfully validated, receive, from the CAPIF core function via the transceiver , an onboard API invoker response message including a certificate of the API invoker, wherein the onboard API invoker response message includes an assigned API invoker identifier, ID, and authentication and authorization information, and wherein the certificate of the API invoker is generated by the CAPIF core function , after a successful validation of the onboarding credential. <EOS>