Computer systems, methods, and computer readable media for facilitating a secure transaction are provided in which a client application is executed on a client computer. The client application initiates a request to a first domain comprising (i) a credential for the client application, (ii) a transaction identifier that uniquely identifies the request, and (iii) optionally, an identification of a user of the client application. Responsive to this request, the client receives a validated transaction module from the first domain. The client application loads the validated transaction module into a separate domain security sandbox that is segregated from memory space in which the client application is run. The validated transaction module conducts a validated transaction between the second domain and the validated transaction module. Separately, through the client application, a determination is made as to whether the transaction is complete by querying the first domain.