About OpenSource:

Of benefit to users, Open Source software is licensed so you can download and use the software free-of-charge. The source code for this software is made available free-of-charge, you (or a programmer you hire) can make changes to this software to better meet your needs, and you can release your changed code back to the community passing the benefit on to other users.

The exact license terms used by this project on their project summary page and in the licensing documents included in their downloads.