It seems that Hadoop, by offering lower cost distributed computing, did as much to advance Big Data as any other software solution. So certainly any list of open source Big Data platforms will start with Hadoop. Yet as the rise of Spark shows, Hadoop may be a founding pioneer – and may well retain its place as the foundation of Big Data – but will not of course be its sole cornerstone. So think of this list (which does indeed start with Hadoop) as a glimpse of the pioneering days, the true infancy, of Big Data.