TeaVM ( https://teavm.org/ ) is an Apache-licensed project, free for use in commercial projects. It is mature and used widely, including in frameworks like Flavour ( https://frequal.com/Flavour/book.html ) and more projects listed here: https://www.frequal.com/TeaVM/TeaVmBasedSites.html
TeaVM compiles Java code to run in the browser, efficiently and quickly. It features short build times, small downloadable files, and a batteries-included toolset (including minification, tree-shaking, and packaging). Previous releases have conquered all similar open-source tools (that support threading) in independent testing: https://renato.athaydes.com/posts/comparing-jvm-alternatives...