Good news! You may use Rixxi under the terms of either the New BSD License or the GNU General Public License (GPL) version 2 or 3.
The BSD License is recommended for most projects. It is easy to understand and it places almost no restrictions on what you can do with the framework. If the GPL fits better to your project, you can use the framework under this license.
You don't have to notify anyone which license you are using. You can freely use Rixxi in commercial projects as long as the copyright header remains intact.
Copyright (c) 2014 Michal Gebauer (http://mishak.net) All rights reserved.
Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice,
this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
* Neither the name of "Rixxi" nor the names of its contributors
may be used to endorse or promote products derived from this software
without specific prior written permission.
This software is provided by the copyright holders and contributors "as is" and any express or implied warranties, including, but not limited to, the implied warranties of merchantability and fitness for a particular purpose are disclaimed. In no event shall the copyright owner or contributors be liable for any direct, indirect, incidental, special, exemplary, or consequential damages (including, but not limited to, procurement of substitute goods or services; loss of use, data, or profits; or business interruption) however caused and on any theory of liability, whether in contract, strict liability, or tort (including negligence or otherwise) arising in any way out of the use of this software, even if advised of the possibility of such damage.
GPL licenses are very very long, so instead of including them here we offer you URLs with full text: