FontForge
· FontForge is a free (libre) font editor for Windows, Mac OS X and GNU+Linux. Use it to create, edit and convert fonts in OpenType, TrueType, UFO, CID-keyed, Multiple Master, and many other formats.
Download JD-GUI to open JAR file and explore Java source code file (.class .java)
Click menu "File → Open File..." or just drag-and-drop the JAR file in the JD-GUI window FontForge-20170731.jar file.
Once you open a JAR file, all the java classes in the JAR file will be displayed.
