MIT or GPLv2
A full Elgg package that includes the framework and a core set of plugins is available under version 2 of the GNU General Public License (GPLv2). We also make the framework (without the plugins) available under the MIT license.
The following answers are provided as a convenience to you; they are not legal counsel. Consult with a lawyer to be sure about the answers to these questions. The Elgg Foundation cannot be held responsible for decisions you make based on what you read on this page.
For questions not answered here, please refer to the official FAQ for the GPLv2.
How much does Elgg cost?
Elgg is free to download, install, and use. If you’d like to donate, we do appreciate our financial supporters!
Can I modify the source code?
Yes, but in general we recommend you make your modifications as plugins so that when a new version of Elgg is released, the upgrade process is as painless as possible.
Can I charge my users membership fees?
If I modify Elgg, do I have to make the changes available?
No, if you are using Elgg to provide a service, you do not have to make the source available. If you distribute a modified version of Elgg, then you must include the source code for the changes.
If I use Elgg to host a network, does The Elgg Foundation have any rights over my network?
What’s the difference between the MIT and GPL versions?
Plugins are not included with the MIT version.
You can distribute a commercial product based on Elgg using the MIT version without making your modifications available.
With the GPL licensed version, you have to include make your modifications of the framework public if you redistribute the framework.
Why are plugins missing from the MIT version?
The plugins were developed under the GPL license, so they cannot be released under an MIT license. Also, some plugins include external dependencies that are not compatible with the MIT license.
May I distribute a plugin for Elgg under a commercial license?
We believe you can, since plugins typically depend only the core framework and the framework is available under the MIT license. That said, we really recommend you consult with a lawyer on this particular issue to be absolutely sure.
Note that plugins released via the community site repository must be licensed under a GPLv2-compatible license. They do not necessarily have to be GPLv2, just compatible (like MIT).
Can we build our own tool that uses Elgg and sell that tool to our clients?
Yes, but then your clients will be free to redistribute that tool under the terms of the GPLv2.