CDDL

CDDL stands for the Common Development and Distribution License. It is a free/open-source software license created by Sun Microsystems for the OpenSolaris project and later maintained as part of the Solaris and related open-source ecosystems. The CDDL is characterized as a weak copyleft license with a file-based approach to copyleft.

The license permits use, modification, and redistribution of the covered code. It requires that the source code for modified versions of CDDL-covered files be made available under the same license terms. When distributing a work that combines CDDL-covered code with other code, the CDDL's terms apply to the portions that are derived from the CDDL-licensed files, while other portions may be distributed under different terms. The license also requires preserving copyright notices and the license text with any redistribution and prohibits implying endorsement by the licensors.

In terms of compatibility, the CDDL is generally viewed as not compatible with the GNU General Public License version 2, which can complicate combining CDDL code with GPLv2-licensed software in a single distribution. The license is recognized as an OSI-approved open source license, and it has influenced the governance of Solaris-derived projects and some related software ecosystems. Critics sometimes describe the CDDL as preserving certain copyleft protections while avoiding some of the broader reach of stronger copyleft licenses, whereas supporters emphasize its balance between openness and practical use in large, mixed-license environments.

Notable usage of the CDDL includes its original role in OpenSolaris and related Solaris-origin code, such as the now-famous ZFS file system in certain distributions and commercial deployments.