How to open Javadoc JAR file in web browser Rename the file flatpack-examples-4.0.18-javadoc.jar to flatpack-examples-4.0.18-javadoc.zip Use your favourite unzip tool (WinRAR / WinZIP) to extract it, now you have a folder flatpack-examples-4.0.18-javadoc Double click index.html will open the index page on your default web browser. How to generate Javadoc from a source JAR? Running the command javadoc: javadoc --ignore-source-errors -encoding UTF-8 -sourcepath "flatpack-examples-4.0.18-sources.jar" -d "flatpack-examples-4.0.18-javadoc" -subpackages