Zope Public License
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| Zope Public License | |
|---|---|
| Name | Zope Public License |
| Author | Zope Corporation |
| Originating author | Jens Vagelpohl |
| Version | 2.1 |
| Spdx | ZPL-2.1 |
Zope Public License The Zope Public License is a permissive free software license used for the Zope family of software and related projects. It has been applied to components developed by entities such as Zope Corporation, contributors associated with Digital Creations, and volunteers from the Python community. The license aims to balance developer attribution requirements with permissive redistribution terms and has influenced licensing discussions among organizations like Free Software Foundation, Open Source Initiative, and projects in ecosystems such as Plone, Django, and Pyramid.
Overview
The Zope Public License provides terms addressing redistribution, modification, and attribution for software originating from the Zope project, aligning with principles promoted by Open Source Initiative, Free Software Foundation, and legal practice in jurisdictions such as the United States and member states of the European Union. It specifies notice and warranty disclaimers relevant to contributors from organizations like Digital Creations and developers who participate in foundations such as the Python Software Foundation and the Apache Software Foundation. The license's text is compact and designed to be applied to libraries, frameworks, and web application components used by projects including Plone, Groonga, and various Zope-adjacent packages.
History and Development
The license originated in the late 1990s alongside the growth of the Zope web application server, with stewardship by entities tied to Zope Corporation and contributors who later engaged with projects such as Plone and foundations like the Python Software Foundation. As debates over permissive versus copyleft licensing intensified involving organizations such as the Free Software Foundation and Open Source Initiative, the Zope Public License underwent revisions to clarify warranty disclaimers, attribution clauses, and compatibility provisions that affected use in ecosystems including Debian, Red Hat Enterprise Linux, and distributions managed by the GNU Project. Prominent developers and institutions active in licensing dialogue—such as maintainers affiliated with SourceForge, contributors to GitHub, and participants from the Linux Foundation—referenced the ZPL when considering alternative permissive licenses like the BSD licenses, MIT License, and Apache License.
License Terms and Conditions
The Zope Public License mandates preservation of copyright notices and an acknowledgment of original authors, with explicit disclaimers of warranty and liability comparable to those in other permissive instruments used by Mozilla Foundation and the Apache Software Foundation. It contains conditions on redistribution, both in source and binary form, and specifies permissible modification and sublicensing approaches that intersect with practices used by projects hosted on platforms such as GitHub, GitLab, and Bitbucket. The license text addresses attribution expectations for contributors, including individuals and organizations like Zope Corporation or contributors who later joined projects such as Plone or Django-related initiatives. Its provisions on patent rights and contribution handling have been considered alongside frameworks like the Apache License patent clauses and the contributor agreements used by the Open Source Initiative signatory projects.
Compatibility and Classification
The Zope Public License is generally regarded as a permissive license, and its compatibility with other licenses has been evaluated by organizations such as the Open Source Initiative and distributions such as Debian GNU/Linux and Fedora Project. Comparisons frequently cite the MIT License, BSD licenses, and the Apache License to illustrate differences in attribution, patent language, and compatibility with copyleft licenses such as the GNU General Public License. Legal practitioners and institutions including law clinics at universities and advisory bodies associated with the Free Software Foundation have analyzed the ZPL for reuse in combined works involving code under licenses from entities like the Eclipse Foundation and the Linux Foundation.
Adoption and Use in Projects
The Zope Public License has been adopted by projects in the Zope ecosystem, including major applications like Plone and numerous packages in the Python Package Index. Organizations and communities such as the Plone Foundation, maintainers of content management projects, and developers contributing to web frameworks have used the license for libraries, middleware, and utilities. Hosting platforms and package repositories including PyPI, Debian, and RPM Fusion have housed software under the ZPL, while collaborative development environments like SourceForge and GitHub have tracked contributions governed by its terms. Institutions involved in research computing and academic software distribution have occasionally selected the ZPL for its balance of permissiveness and attribution requirements.
Criticisms and Controversies
Critics have pointed to aspects of the Zope Public License that may complicate compatibility with stronger copyleft regimes such as the GNU General Public License and have debated whether its attribution requirements are more burdensome than those in the MIT License or BSD licenses. Legal scholars, representatives from the Free Software Foundation, and maintainers from projects audited by organizations like the Open Source Initiative have raised questions about wording related to patent rights and contributor warranties. Discussions in forums frequented by contributors to Plone, Zope, and other Python-centric projects have highlighted disputes over relicensing, contributor agreements, and downstream redistribution practices involving package maintainers and corporate adopters.