I use TeaVM exclusively now to build web apps. It is rock solid and performant in every respect including runtime speed and download size. It is great alone or in conjunction with its SPA toolkit Flavour (https://blogs.oracle.com/javamagazine/java-in-the-browser-wi...)

Some examples:

* MerchMaker (make Roblox merch): https://frequal.com/merchmaker/

* Funniest Stories Ever (fill in the blank stories): https://fse.frequal.com

* CoronaWait (store wait times and in-stock reports): https://coronawait.frequal.com/