Andrey gave a thorough summary of all four libraries. Here's my personal experience with two of them. At my job we use both JYaml and SnakeYAML. We started with JYaml in the 2007-2008 timeframe when it appeared to be active. It has API similarities with XStream, which is a benefit for us. I introduced SnakeYAML in mid-2009 when I encountered a bug in JYaml and noticed there have been no new JYaml