The cajo project source code is free software, licensed to you under the terms of the GNU Lesser General Public Licence (LGPL) version 3, or at your option, any later version, published by the Free Software Foundation.
Allow me to summarise what I feel are the four most important bits:
Many will assert this last point, makes the licence less free than the GNU General Public Licence (GPL). However, just as with objects, this library is intended to allow developers to work together: whether they have the option to make their code free, or not.
However, this licence does permit extending these classes, and implementing these interfaces, in your own packages; without becoming subject to Copyleft. To summarise: Your application may, or may not, be free -- yet this library, and any modifications to it, must always be free.
Project Documentation Licence: Copyright © 2004 John Catherino.
Permission is granted to copy, distribute, and modify the cajo project web pages, wiki pages, forum pages, and blog pages under the terms of the GNU Free Documentation Licence (GFDL), version 1.3 or at your option, any later version published by the Free Software Foundation. The cajo project documentation contains no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.