Clirr is a tool that checks Java libraries for binary
compatibility with older releases. Basically you give it two sets
of jar files and Clirr dumps out a list of changes in the public
api. Clirr provides an Ant task that can be configured to break
the build if it detects incompatible api changes. In a continuous
integration process Clirr can automatically prevent accidental
introduction of binary compatibility problems in Java libraries.