Server Side Public License
ess-ess-pee-ELL
A source-available license that requires anyone offering the software as a service to open source their entire stack.
The SSPL was created by MongoDB in 2018. It is based on the GPL but adds a critical clause: if you offer the software as a service, you must open source not just the software itself but your entire service stack, including management, monitoring, and deployment tools.
This requirement is so broad that it effectively prevents cloud providers from offering a competing managed service. That was the point. MongoDB created SSPL specifically to stop AWS, Azure, and GCP from offering MongoDB as a managed database service without contributing back or paying for a license.
The Open Source Initiative rejected SSPL as an open source license. The Linux Foundation and others agree. The license is technically source-available, not open source. Elastic also adopted SSPL for Elasticsearch in 2021 (though they later switched to AGPL). The BSL takes a time-based approach to the same problem.
Examples
MongoDB relicenses from AGPL to SSPL.
AWS was offering DocumentDB, a MongoDB-compatible database service. SSPL made it legally risky for any cloud provider to offer a managed MongoDB service without a commercial license. AWS continued with DocumentDB but could not use MongoDB's code directly.
A company evaluates an SSPL-licensed product.
The company wants to use the product internally. SSPL allows that without any issues. The restriction only kicks in if they offer the software as a service to others.
A cloud provider considers offering a managed version.
To comply with SSPL, they would need to open source every tool in their stack used to deploy and manage the service. That includes proprietary orchestration, billing, and monitoring systems. They decide to build an alternative instead.
Frequently asked questions
Is SSPL an open source license?
No. The Open Source Initiative explicitly rejected SSPL as an open source license. It is source-available. You can read the code and use it, but the service-offering restriction goes beyond what open source allows.
Can I use SSPL software in my company?
Yes. SSPL allows internal use without restrictions. The license only triggers its broad copyleft requirements if you offer the software as a service to third parties.
Related terms
A source-available license that restricts commercial use for a set period before converting to a fully open source license.
A copyleft open source license that requires derivative works to also be distributed under the GPL.
The practice of tracking and fulfilling the legal obligations of all open source software used in a product.
A permissive open source license that allows anyone to use, modify, and distribute the software with minimal restrictions.
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