This project contains multiple licenses depending on the sub-project. 
Check each sub-project individually.

* JSweet transpiler: GPLv3
* JSweet core: Apache 2
* JDK runtime (J4TS): Apache 2
* JSweet candy generator: GPLv3
* JSweet documentation: CC-BY-SA
 
DISCLAIMER: JSweet licensing is designed so that one can use JSweet to 
program closed-source and commercial applications. JSweet Java to TypeScript 
transpilers are under GPL and all the APIs are in Apache 2, which makes it 
very clear that you can build commercial applications using JSweet (similarly 
to when using GNU's GCC C/C++ compiler, which is also a GPL software).

Constraints of the GPL only hold when using/modifying JSweet source code of 
the transpiler and/or of the candy generator. If you want to embed the 
transpiler or the candy generator in a non-open source commercial project, 
please contact Renaud Pawlak for discussing a commercial license.