Zope is made available under the Zope Public License. This license seeks to allow free use of Zope and its source given a few conditions for use.

Our goals are to allow Zope to flourish as an open source project while making sure that we get some credit for having originally developed Zope.

The 2.1 version of the license is reusable. It supports having a consistent license for Zope and third-party products without requiring 3rd-party developers to assign copyright to Zope Corporation.

It is important that add-on products for Zope be released under the ZPL. Why? Two reasons:

• The ZPL is a flexible license that supports both commercial and non-commercial use of the software.
• If Zope add-on products are released under the ZPL, then users of Zope and the add-on products only have one license to worry about. Keeping track of many different licenses is a burden to users.

Software can be released under multiple licenses. For example, software can be released under both the ZPL and the GPL.

We will update the Zope software to use ZPL 2.1. This does not change the rules for contributing to the Zope software repository. Contributions to the Zope repository will still be owned by "Zope Corporation and Contributors".

To use the ZPL 2.1 license, just include the license with your software and also include a separate copyright statement (sample).

We have updated to the 2.1 version. The license though, like Zope itself, is a work-in-progress. We would love to hear your ideas on the license. Please send your comments on the license to [email protected].

This license has received OSD branding. Zope Corporation is working to stay true to the spirit of the Open Source Definition and its stated rationales. This license has been confirmed as GPL compatible by the FSF.

Changes

• 2.1 Reusable ZPL separates copyright information into an accompanying copyright file, COPYRIGHT.txt
• 2.0 New license, now GPL compatible
• 1.1 Changed from Digital Creations to Zope Corporation, removed previous clause asking for (but not requiring) attribution, changed Open Source (tm) to open source until trademarking issues are resolved, changed links from "www.zope.org" to "www.zope.com".
• 1.0 Official release.
• 0.9.7 Dropped the requirement for "Attribution". Replaced the requirement with a "plea", but made it voluntary.
• 0.9.6 Clarified the "Attribution" clause. It stated that both a "button" and a "credits page" were required. The updated wording clearly states that the "button" links to the "credits page". This "credits page" resides on Digital Creations' web site by default, but may be copied to the attributing web site.
• 0.9.5 Added a line to clause #3 regarding the avoidance of attribution. In clause #4, dropped the requirement to attribute in technical papers. Also in clause #4, added that intact distributions need not have an attribution in any advertising. In clause #6, added the word "Modified", and added a restatement that intact distributions don't require attribution. In clause #7, added a clarification regarding patches and modifications. Added two sentences to the attribution section reiterating the clarification from clause #3 regarding sites that have valid reasons not to attribute the use of Zope in the required manner.
• 0.9.4 Corrected a typo in first paragraph and labeled the disclaimer section.
• 0.9.3 The stipulation about being on every page with a copyright was ill-conceived and has disappeared.
• 0.9.2 Received a complaint about clause 7. I changed it to better reflect our goal, which is to ensure patch integrity and minimize the forked version problem. I'm open to suggestions on this.