Clirr is a tool that checks Java libraries for binary and source 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 Maven Plugin can be used to break the build if it detects incompatible API changes. In a continuous integration process Clirr can automatically prevent accidental introduction of binary or source compatibility problems.
Clirr is provided by the SourceForge project with the same name and may be used under the terms of the GNU Lesser General Public License.