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Business Source License (BSL)

The Business Source License (BSL) is a source-available license that allows free use with specific limitations and automatically converts to an open source license after a set time period.

What is the Business Source License (BSL)?

The Business Source License (BSL) is an innovative source-available license created by MariaDB founder Michael "Monty" Widenius. The BSL implements a unique time-delayed approach to licensing: it begins with source-available terms that include commercial use restrictions, but automatically converts to a specified open source license (typically GPL or Apache) after a predetermined period (usually 3-4 years).

This temporal approach creates a middle ground between proprietary and open source licensing models, allowing software creators to monetize recent versions while ensuring all code eventually becomes fully open source. The BSL is sometimes referred to as a "time-delayed open source" model.

Key Features of the BSL

The BSL has several distinctive characteristics:

1. Time-Limited Commercial Restrictions

The BSL imposes specific "Additional Use Grant" limitations that typically restrict using the software to compete with the licensor's commercial offerings. These restrictions automatically expire after a specified "Change Date" (typically 3-4 years from release).

2. Guaranteed Open Source Conversion

On the Change Date, the license automatically converts to a specified open source license (the "Change License"), with no action required by the licensor or users.

3. Source Code Availability

Throughout both the restricted and open source phases, the complete source code is available for viewing, modification, and non-restricted uses.

4. Customizable Use Grants

Licensors can define the specific restricted uses in the "Additional Use Grant" section, allowing customization to their business model.

BSL License Structure

A BSL license typically contains these key sections:

  1. License Parameters: Defining the licensor, licensed work, additional use grants, change date, and change license.

  2. Additional Use Grant: Specifying what commercial uses are permitted during the restricted phase.

  3. Change Date: The date when the license automatically converts to the specified open source license.

  4. Change License: The open source license that will apply after the Change Date (commonly GPL or Apache 2.0).

  5. Standard BSL Terms: The core legal text that defines the mechanics of the license.

Example BSL License Text

The Licensor hereby grants you the right to copy, modify, create derivative works, redistribute, and make non-production use of the Licensed Work. The Licensor may make an Additional Use Grant, above, permitting limited production use.

Effective on the Change Date, or the fourth anniversary of the first publicly available distribution of a specific version of the Licensed Work under this License, whichever comes first, the Licensor hereby grants you rights under the terms of the Change License, and the rights granted in the paragraph above terminate.

If your use of the Licensed Work does not comply with the requirements currently in effect as described in this License, you must purchase a commercial license from the Licensor, its affiliated entities, or authorized resellers, or you must refrain from using the Licensed Work.

All copies of the original and modified Licensed Work, and derivative works of the Licensed Work, are subject to this License. This License applies separately for each version of the Licensed Work and the Change Date may vary for each version of the Licensed Work released by Licensor.

You must conspicuously display this License on each original or modified copy of the Licensed Work. If you receive the Licensed Work in original or modified form from a third party, the terms and conditions set forth in this License apply to your use of that work.

Any use of the Licensed Work in violation of this License will automatically terminate your rights under this License for the current and all other versions of the Licensed Work.

This License does not grant you any right in any trademark or logo of Licensor or its affiliates (provided that you may use a trademark or logo of Licensor as expressly required by this License).

TO THE EXTENT PERMITTED BY APPLICABLE LAW, THE LICENSED WORK IS PROVIDED ON AN “AS IS” BASIS. LICENSOR HEREBY DISCLAIMS ALL WARRANTIES AND CONDITIONS, EXPRESS OR IMPLIED, INCLUDING (WITHOUT LIMITATION) WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, NON-INFRINGEMENT, AND TITLE.