Under the present invention, source input corresponding to a first release of Java byte code and target input corresponding to a second release of the Java byte code is received. The input is transformed into a first list containing class names associated with the first release and a second list containing class names associated with the second release. Thereafter, any classes corresponding to class names that appear on both lists (e.g., matching class names) are loaded. The methods within the matching classes are then compared to determine if any of the APIs have been modified between the two releases. After the comparison, the matching class names are removed from the lists. Any class names remaining on the first list represent APIs that have been removed from the second release, while any class names remaining on the second list represent APIs that have been added for the second release.