Abstract: A mobile payment system (MPS) is disclosed that enables transactions for MPS users using user devices, and interfaces with third party payment systems with third party user accounts. The MPS includes MPS frontends, third party MPS accounts, and a MPS backend including a MPS backend account, a MPS database and MPS user accounts. Each MPS frontend is located on one user device and is associated with one MPS user. At least one of the third party MPS accounts is on each third party payment system. Each MPS user account is associated with at least one MPS user. A particular MPS frontend performs local processing of MPS functions on its user device and communicates over networks with the MPS backend and with other MPS frontends on other user devices. The MPS backend administers funds in the MPS backend account, the MPS user accounts, and the third party MPS accounts.