Business Source License
bee-ess-ELL
A source-available license that restricts commercial use for a set period before converting to a fully open source license.
The Business Source License is a source-available license created by MariaDB. The code is visible to everyone, but commercial use is restricted for a set period (typically 3-4 years). After that period, the license automatically converts to a permissive open source license like Apache 2.0.
BSL gained attention when HashiCorp switched Terraform, Vault, and other products from the Mozilla Public License to BSL in 2023. Sentry, CockroachDB, and MariaDB also use variants. The motivation is always the same: prevent cloud providers from offering a competing hosted version of the product without contributing back.
The open source community has mixed feelings. The Open Source Initiative does not consider BSL an open source license because of the commercial use restriction. But many companies see it as a pragmatic middle ground between fully open source (where AWS can clone your product) and fully proprietary (where users cannot see the code). The SSPL takes an even more aggressive approach to the same problem.
Examples
A company switches from an open source license to BSL.
HashiCorp relicenses Terraform under BSL 1.1. Users can still read the code and use it internally. But a cloud provider cannot offer 'Terraform as a Service' without a commercial license from HashiCorp.
A startup evaluates using a BSL-licensed database.
The startup can use CockroachDB freely for their own product. But if they want to offer a managed CockroachDB service to others, they need a commercial agreement with Cockroach Labs.
The BSL change date arrives.
Code released under BSL 1.1 with a 4-year change date and Apache 2.0 as the change license. Four years later, that specific version automatically becomes Apache 2.0 licensed. Anyone can use it commercially.
Frequently asked questions
Is BSL an open source license?
No. The Open Source Initiative does not recognize BSL as open source because it restricts commercial use. It is categorized as 'source available,' meaning the code is visible but not freely usable for all purposes.
Why did HashiCorp switch to BSL?
HashiCorp wanted to prevent cloud providers from offering competing hosted versions of their tools without contributing back. BSL lets users see and use the code internally while restricting competing commercial offerings.
Related terms
A source-available license that requires anyone offering the software as a service to open source their entire stack.
A copyleft open source license that requires derivative works to also be distributed under the GPL.
A permissive open source license that allows anyone to use, modify, and distribute the software with minimal restrictions.
The practice of tracking and fulfilling the legal obligations of all open source software used in a product.
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