LAME MP3 encoder (lamejs)
MP3 files are encoded with lamejs 1.2.1, a JavaScript port of the LAME encoder, licensed under the GNU Lesser General Public License 3.0. It is loaded as a separate, unmodified file (/assets/vendor/lame.min.js); its license text is at lame.LICENSE.txt and its source code at github.com/zhuker/lamejs. You may replace it with your own build.
Everything else
The audio engine, effects, time-stretch, analysis and interface are WaveTinker's own code.