The GameBreaker project itself is licensed under GPLv2, with code taken and/or inspired from UndertaleModTool (GPLv3) and DogScepter (MIT)
Below is a closer-to-exhaustive list of various resources used:
GameBreaker utilizes research and code by myself, as well as the hard work of others, including:
- krzys-h/UndertaleModTool
- colinator27/DogScepter
- PoroCYon
- pcy.ulyssis.be/undertale (mirror of Mirrawr's site)
- PoroCYon/Altar.NET
- and several gists