This document discusses several open source blockchain platforms, including Eris, HydraChain, MultiChain, OpenChain, and others. Eris allows anyone to create and run applications from anywhere using blockchain or smart contract technology. HydraChain is highly compatible with Ethereum and has instant finality. MultiChain enables permissioned chains and instant deployment. OpenChain is suited for managing digital assets flexibly in a robust manner. The document provides brief descriptions of the key features of these various open source blockchain platforms.