A computing system implements a network transaction service. Users of the network transaction service can launch a service application to indicate a transaction at a location of a merchant. A transaction data set is then received from a point-of-sale terminal of the merchant, which enables the computing system to fund the transaction from a shared funding source of the network transaction service. Subsequently, the computing system can access a customer account of the user to reimburse the shard funding account for an amount corresponding to the transaction.