Common Public Licenses

Permissive Licenses

CC0 (Creative Commons CC0)

• Complete waiver of all rights
• SQLite, Ethereum Name Service domains, many government datasets

CC-BY (Creative Commons Attribution)

• Allows all uses with attribution
• Wikipedia, many academic papers

MIT

• Extremely simple and clear to understand
• Allows use in proprietary software with minimal restrictions
• Only requires preservation of copyright and license notices
• Lacks express patent rights protection
• Limited protection for original authors
• NodeJS, Angular.js, Bootstrap

Apache

• Includes express patent license protection
• Allows proprietary modifications
• Clear documentation requirements for changes
• Apache HTTP, Kubernetes, OpenStack

Copyleft Licenses

GNU General Public License (GPL)

• Ensures derivative works remain open source
• Strong community support
• May create licensing conflicts with other software
• Requires source code disclosure for derivatives
• Git, Linux Kernel, WordPress

Lesser GPL (LGPL)

• More flexible than GPL for library linking
• Allows proprietary software to use LGPL libraries
• Balance between openness and practicality
• Complex compliance requirements
• OpenCV, GTK, old Qt

SSPL (Server Side Public License)

• Extends beyond traditional copyleft requirements
• More restrictive than standard copyleft licenses
• Requires release of all service-related code, including management and infrastructure code
• Not recognized as open source by OSI due to its restrictive nature
• Mongo DB, Redis, ElasticSearch

MPL (Mozilla Public License)

• Files containing MPL code must remain under MPL
• Allows mixing with proprietary code in larger works
• Only requires source code disclosure for modified MPL components
• Can be combined with other licenses in a larger project
• Permits integration into proprietary codebases while keeping MPL components open
• Firefox, old Terraform, Thunderbird

CC BY-NC-ND (Creative Commons Attribution-NonCommercial-NoDerivatives)

• Allows sharing and adaptation with attribution
• Prohibits commercial use and derivatives
• Strongest protection for creators
• Many academic papers, digital art, online courses

Not Open Source

BSL (Business Source License)

• Not copyleft or permissive license
• Hybrid approach with time-based transitions
• Source code is available but with usage restrictions
• Converts to open source (typically MPL 2.0) after a specified period
• Restricts competitive commercial use while allowing most other uses
• new Terraform

Sources

• Open Source Initiative Licenses
• Creative Commons Licenses
• GPL Licenses
• Mozilla Licenses
• SSPL / MongoDB License
• BSL / Terraform License