The source code is available via the website and appears to be licensed under the GPLv2.
The program itself however, has additional terms of service which would appear to be in stark contradiction to the license itself, vis-à-vis:
BY USING THE VUZE PLATFORM YOU AGREE NOT TO:
8.10 use the Vuze Platform if You are under the age of eighteen (18) years old;
8.12 reverse engineer, decompile, disassemble or otherwise attempt to discover the source code of the Vuze Platform or any part thereof, except and only to the extent that such activity is expressly permitted by applicable law notwithstanding this limitation;
8.13 modify, adapt, translate or create derivative works based upon the Vuze Platform or any part thereof, except and only to the extent that such activity is expressly permitted by applicable law notwithstanding this limitation;”
I guess the question is, what is the “Vuze Platform” exactly? If it’s build on GPL software then they simply cannot do this.
Wikipedia has this to say:
Up to version 22.214.171.124, Azureus was distributed under the GNU General Public License (GPL); beginning with the version 3 distribution, the license presented upon installation changed. While it still states that the “Azureus Application” is available under the GPL, completing installation requires the user to agree to the terms of the “Vuze Platform”, which include restrictions on use, reverse-engineering, and sublicensing. As with many similar licenses, the Azureus licence includes a prohibition on use of the software by people “under the age of 18”. Allegedly, the TOS only applies to the website, vuze.com, and not the software, however the actual TOS include the application as part of the platform.