Secure real-time transactions

A method including receiving, at a mobile device being used by a consumer, a transaction code from a point-of-sale terminal at a store of a merchant. The transaction code can include a merchant public identifier being associated with the merchant, a payment amount for one or more items to be purchased from the merchant by the consumer in a transaction, a transaction identifier for the transaction, and a digital signature. The method also can include verifying the digital signature for the transaction code. The method additionally can include sending, from the mobile device, a request to pay the merchant for the payment amount from a first account of the consumer maintained by a first financial institution, such that the first financial institution, upon receiving the request to pay, retrieves from a transaction system an account identifier of a second account of the merchant maintained by a second financial institution based on the merchant public identifier, such that the first financial institution sends to the transaction system payment information regarding a payment to be made to the second account from the first account, such that the payment information is routed through the transaction system to the second financial institution, and such that the point-of-sale terminal receives a notification of payment for the transaction in real-time while the consumer remains at the store of the merchant. The transaction system can be maintained by an entity that is different from the merchant, the first financial institution, and the second financial institution. The payment information can include the transaction identifier, the account identifier of the second account, and the payment amount. Other embodiments are provided.