JaValid is an open source framework for validating your Java business objects. JaValid is licensed under the Eclipse Public License 1.0. JaValid 1.2 is the latest release.
JaValid is an annotation-based validation framework, which allows you to annotate your Java objects to introduce validation. JaValid can be used in any type of Java application (standalone application, web application etc). The framework currently provides full integration with the Spring Framework, Java Server Faces, Facelets, and any database. The framework can be extended easily, by means of extensions, and also allows you to add your own validation constraints in addition to the ones shipping with the framework.
The source and distributions are hosted on sourceforge, go to the downloads directly here. You may also want to check out the weblog, which contains some useful information, including several examples.
Have fun using JaValid!