SSPL

The Server Side Public License (SSPL) is a copyleft software license published by MongoDB, Inc. in 2018. It is designed for server software and is a modification of the GNU Affero General Public License (AGPL) version 3.

Key clause: If you make the licensed program available to third parties as a service, you must distribute complete corresponding source code under SSPL for the entire service, not only the program's own source.

Purpose: The license was introduced to close what its proponents describe as the “SaaS loophole,” the ability of providers to offer the software as a service without releasing their own modifications or the rest of the service’s code.

Scope: It applies to MongoDB's server distribution and derivatives released under SSPL. The license requires that anyone operating the program as part of a publicly offered service makes the service's source code available under the same license terms.

Reception: The SSPL has been controversial. Advocates argue that it ensures users and auditors can study and modify the software used in a service, while opponents say it is overly restrictive and not truly open source under widely cited definitions. The Open Source Initiative (OSI) has stated that the SSPL is not an open source license, and as a result many distributions and cloud providers avoid using or distributing SSPL-licensed software.

Impact: The license has intensified discussions about licensing for cloud services and the governance of open source licenses, but it has not achieved broad adoption beyond MongoDB’s ecosystem.

History: MongoDB introduced the SSPL in 2018 in response to cloud providers offering MongoDB as a service; the license is primarily associated with MongoDB’s server software and its ecosystem.