BuddyCast is an open peer-to-peer protocol for distributing streaming content to an unlimited number of users by turning broadcast receivers into stream relays, or "buddies." Developed by Mel Beckman, Dennison Bollay, and Brian Fox. The protocol maintains resilience through the use of standby redundant buddies to replace buddies that leave the network. Broadcast distribution is controlled by a Buddycast Multicast Controller (MC), which hands off inbound requests for streams to available buddies and monitors the state of relayed streams. To this end, the MC maintains a network topology map, which the MC can exploit to improve performance and minimize the number redundant inter-network streams.

Because the number of available relays grows along with the number of receivers, Buddycast can scale to serve an audience of any size. This lets even the smallest broadband Internet user distribute streaming content to a large audience. Because content is sent only to willing receivers, the total bandwidth consumed on the Internet will always be less than an equivalent unicast broadcast -- typically much less, as the MC only handles connection requests and buddy management. The latest BuddyCast documents are: