A financial transaction system providing a financial switching engine, the financial transaction system comprising: a distributed plurality of different physical data centres implemented at different respective physical locations, connected together via a private network; a plurality of plugins each configured to perform a different respective function of the financial transaction system; and an operating system on which the plugins run, the plugins being configured to communicate messages with one another in order to perform financial transactions; wherein the plugins are distributed amongst some or all of the data centres and the operating system is configured to abstract the plugins from the distributed data centres, such that the plugins communicate said messages with one another via the operating system without needing to specify particular ones of said data centres as destinations of the messages, while the operating system handles routing of the messages between the data centres over the private network without the plugins needing visibility of the routing.