GLOSSARY / DEFINITION
What is a source available license
A source available license publishes the source code for you to read and usually modify, while attaching use restrictions that a true open source license does not impose. The phrase is precise and the distinction matters, because a source available license is not open source, and software can move from one to the other while it is already running in your production environment.
Definition
A source available license is a software license under which the source code is made public, so you can inspect and often modify it, but the right to use that code carries conditions that an open source license would not allow. Those conditions typically restrict how the software may be used in production, most often by limiting competitive use or the offering of the software as a service to others. The defining feature is the combination: visible source plus a use restriction. That second part is what separates source available from open source, and it is the part that creates risk for a buyer.
How it differs from open source
Open source has a formal meaning. Under the definition maintained by the Open Source Initiative, an open source license must allow use for any purpose, with no restriction on the field of use and no discrimination against persons, groups, or endeavors. Source available licenses fail that test on purpose, because they restrict use to protect the vendor's commercial interest. Reading the source code is not the question. The question is what you are permitted to do with it. A permissive open source license such as Apache 2.0 places almost no conditions on use. A source available license such as the Business Source License or the Server Side Public License publishes the same kind of code but conditions the use, which is why neither is approved by the Open Source Initiative.
Why it matters for production risk
The reason this definition is worth getting right is that several widely used tools have moved from open source to source available terms in recent years. HashiCorp moved Terraform, Vault, Consul, Nomad, and Packer to the Business Source License as of August 2023. Redis moved to source available terms as of March 2024. Elasticsearch and Kibana moved to the Server Side Public License as of 2021, and MongoDB did so in 2018. In each case the change attached new conditions to software that organizations were already running. For most internal deployments these licenses still permit the use, but the burden shifts to you to confirm that, and a specific deployment such as a hosted service can fall inside a restriction. The exposure is not theoretical. It applies to production you already own.
Related reading
For why this distinction carries real weight, see why source available is not open source. For how the license families compare, read permissive, copyleft, and source available explained. Both sit alongside the rest of our open source license risk glossary.
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Questions buyers ask.
What is a source available license?
A source available license is one that publishes the source code so you can read and often modify it, while placing use restrictions that an open source license does not. The code is visible, but conditions such as limits on competitive or service use sit on top of it. Source available is not the same as open source, and these licenses are not approved by the Open Source Initiative.
Is source available the same as open source?
No. Open source, as defined by the Open Source Initiative, allows use for any purpose without field of use restrictions. Source available licenses publish the code but restrict how it may be used, for example by limiting competitive production use. Examples include the Business Source License and the Server Side Public License, neither of which is approved by the Open Source Initiative.
Why do source available licenses matter to enterprises?
They matter because software already running in production can change from open source to source available, attaching restrictions to use that was previously unconditioned. The most common concern is a limit on offering the software as a service or in competition with the vendor, which can affect specific deployment patterns. The exposure applies to current production, not only new adoption.
Which licenses are source available?
Well known examples include the Business Source License, used by HashiCorp for Terraform and other tools as of August 2023, the Server Side Public License, used by MongoDB, Elastic, and Redis, and the Redis Source Available License. Each publishes source code while restricting certain uses, which is why they are grouped as source available rather than open source.
Is this legal advice?
No. This is commercial and licensing risk advisory, not legal advice. For interpretation of a source available license and how its terms apply to you, engage your own counsel.