Server Side Public License

The Server Side Public License (SSPL) is a source-available copyleft software license introduced by MongoDB Inc. in 2018.

It includes most of the text and provisions of the GNU Affero General Public License version 3 (AGPL v3), but modifies its provisions for software that is conveyed over a network—requiring that anyone who offers the functionality of SSPL-licensed software to third-parties as a service must release the entirety of their source code, including all software, APIs, and other software that would be required for a user to run an instance of the service themselves, under the SSPL. In contrast, the AGPL v3's equivalent provision covers only the licensed work itself.

The SSPL is not recognized as free software by the Open Source Initiative (OSI), Red Hat, or Debian as the aforementioned provision is discriminatory towards specific fields of use. Specifically, it is asserted that this is discriminatory against users of the software who use proprietary software within their stack, as the license requires the open-sourcing of every part interacting with the service, which under these circumstances might not be possible. This is in violation of criteria 6 and 9 of the Open Source Definition as used by the Open Source Initiative.