BLOCKCDN is a distributed CDN built on block chain. On BLOCKCDN, all traffic data and acceleration data are recorded in block chain and no one can tamper with them. Walking through the world's massive nodes, so that users can access the accelerated website can be assigned to the nearest node, real-time response. BLOCKCDN develops a self-service CDN trading market based on ethereum smart contract, enabling website owners and sharers to trade freely, equally and transparenly.