Permissions, conditions and limitations at a glance
Conditions
- Notice for source distributionThe notice is only required when distributing in source form, not for binaries.
Limitations
- LiabilityExpressly states that there is no liability for damages.
- WarrantyExpressly states that no warranty is provided.
Permissions, conditions and limitations are classified using data from choosealicense.com (GitHub, MIT License).
What kind of license is it?
The Boost Software License 1.0 was created in 2003 for the Boost collection of C++ libraries. It is a permissive license similar to MIT, but differs in that its condition applies only to copies in source form. The copyright notice and license text must be included in all copies of the software, in whole or in part, unless those copies are solely in the form of machine-executable object code generated by a source language processor (compiler). Boost and the Catch2 testing framework, among others, use it.
Why this condition?
With C++ template libraries, header code is compiled directly into the user's executable. Under MIT, a notice would be required every time that executable is distributed; the BSL removes this burden so that end-user products built with the library do not need a notice screen.
What you must do when distributing
- When distributing source code, retain the copyright notice and license text.
- When distributing only binaries, there is no notice obligation.
Common misconceptions
- "BSL is the Business Source License" — In SPDX,
BSL-1.0is the Boost license. The Business Source License used by MariaDB, HashiCorp and others isBUSL-1.1, an entirely different, source-available license that is not open source. - "No notice is ever needed" — It is needed when you distribute source. The license with no conditions at all is 0BSD.
How to apply it
The Boost convention is to keep the text as LICENSE_1_0.txt and attach the notice "Distributed under the Boost Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at https://www.boost.org/LICENSE_1_0.txt)" to each source file. Choosing the official notice in the generator's "File header" tab produces this text. The SPDX identifier is BSL-1.0.
When it fits
It suits header-only C++ libraries and libraries used in products where a notice screen is hard to provide, such as games and embedded devices.
Can BSL-1.0 code go into another project?
General verdicts for taking code released under this license and distributing it combined into a project under each license below. See other combinations in the compatibility checker →
| Target project | Verdict | Notes |
|---|---|---|
| Proprietary (closed-source) software | Allowed | When distributing as source, keep the original copyright and license text (not required when distributing binaries only). |
| MIT | Allowed | When distributing as source, keep the original copyright and license text (not required when distributing binaries only). |
| Apache-2.0 | Allowed | When distributing as source, keep the original copyright and license text (not required when distributing binaries only). |
| MPL-2.0 | Allowed | When distributing as source, keep the original copyright and license text (not required when distributing binaries only). |
| LGPL-2.1 | Allowed | When distributing as source, keep the original copyright and license text (not required when distributing binaries only). |
| LGPL-3.0 | Allowed | When distributing as source, keep the original copyright and license text (not required when distributing binaries only). |
| GPL-2.0 | Allowed | When distributing as source, keep the original copyright and license text (not required when distributing binaries only). |
| GPL-3.0 | Allowed | When distributing as source, keep the original copyright and license text (not required when distributing binaries only). |
| AGPL-3.0 | Allowed | When distributing as source, keep the original copyright and license text (not required when distributing binaries only). |
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