Open Source software written in Java Open Source Software or OSS for short is software which is available with the source code. Users can read, modify and redistribute the software in the source as well as in the binary format. Means the open source software is all about freedom. Freedom of use and the modification of the code according the requirement. Here are the list of free open source software written in Java. You can use these software without paying any fee or royalty. in Development > Javawith javalibrarieslibraryopenopen-sourcesoftwaresource