A mobile payment platform and service provides a fast, easy way to make payments by users of mobile devices. The platform also interfaces with nonmobile channels and devices such as e-mail, instant messenger, and Web. In an implementation, funds are accessed from an account holder's mobile device such as a mobile phone or a personal digital assistant to make or receive payments. Financial transactions can be conducted on a person-to-person (P2P) or person-to-merchant (P2M) basis where each party is identified by a unique indicator such as a telephone number or bar code. Transactions can be requested through any number of means including SMS messaging, Web, e-mail, instant messenger, a mobile client application, an instant messaging plug-in application or “widget.” The mobile client application, resident on the mobile device, simplifies access and performing financial transactions in a fast, secure manner.