JDiff is a Javadoc doclet which generates an HTML report of all the packages, classes, constructors, methods, and fields which have been removed, added or changed in any way, including their documentation, when two Java APIs are compared. Javadoc is a Documentation generator from Sun Microsystems for generating API documentation in HTML format from Java source code HTML, an initialism of HyperText Markup Language, is the predominant Markup language for Web pages It provides a means to describe the structure This is very useful for describing exactly what has changed between two releases of a product. Only the API of each version is compared. It does not compare what the source code does when executed.