YAAC is licensed as open-source software under version 3 or later of the GNU Lesser General Public License (LGPL), and source code is available under the terms of that license.
Note that some of the third-party components used by YAAC have other licenses. For example, the RXTX library is licensed under the LGPL with a special qualifier for linking to other-licensed software. The Apache Commons libraries are licensed under the Apache license and source code is available on the Apache website at http://commons.apache.org/components.html. The OpenMaptm library (created by BBN) is licensed under a custom open-source license that is not compatible with the GPL (but is compatible with the LGPL); per the terms of that license, the OpenMaptm source code may be downloaded from http://openmap-java.org/. YAAC is presently using OpenMaptm Version 5.0.
The OpenStreetMap data is licensed under either the Creative Commons CC-BY-SA license or the Open Database License. The Shuttle Radar Topographic Mission (SRTM) elevation data has been placed in the public domain by the U.S. Geological Survey.