The widespread deployment of varying networking technologies, coupled with the exponential increase in end-user data demand, have led to the proliferation of multi-homed or multi-interface enabled devices. To date, these interfaces are mainly utilized one at a time based on network availability, cost, and user-choice. While researchers have focused on simultaneously leveraging these interfaces by aggregating their bandwidths, these solutions however, have faced a steep deployment barrier. In this demo, we demonstrate the OPERETTA optimal bandwidth aggregation system. OPERETTA aims to utilize all the available network interfaces on a mobile device by distributing the users traffic on them. It is implemented as a Layered Service Provider (LSP) in the Windows OS to intercept the network connections from the applications and schedule these connections on the most appropriate interfaces. The network interfaces are chosen with the goal to optimize the overall system power consumption while meeting a certain throughput constraint calculated based on a user defined utility. The demo shows the effect of applying different scheduling algorithms and user utility functions on the system throughput and energy consumption.