OpenCms is true Open Source software from the day is was released in March 2000.
Open Source Software has been so successful in recent years, that the term "Open Source" has found it's way to the marketing departments. As a consequence, many products today are advertised as "Open Source" in some way or the other.
The Open Source Initiative (OSI) is a non-profit corporation formed to educate about and advocate for the benefits of open source and to build bridges among different constituencies in the open-source community. Please check the OSI website for a good definition of what Open Source Software truly means.
The OpenCms core uses the well known GNU Lesser General Public License (LGPL), version 2.1. This license has been developed by the Free Software Foundation (FSF) and is generally accepted as one of the most popular Open Source licenses. It has also already been challenged in a US based court, but was ruled to be valid.
Some modules developed by Alkacon Software are using the GNU Public License (GPL), version 2.1. This license, also from the FSF, is in even more widespread use.
The FSF provides sort of a comparison of the LGPL versus the GPL. Please note that the title of the article may be misleading: We believe the LGPL is the better choice as core license for OpenCms.
Upgrade your existing OpenCms installation to the current stable version 10.0.1 with this easy to use wizard.