vert.x is described as 'From Wikipedia, the free encyclopedia Vert.x is a polyglot event driven application framework that runs on the Java Virtual Machine.' and is an app in the Development category. There are three alternatives to vert.x for a variety of platforms, including Linux, Mac, Windows, BSD and Chrome OS. The best alternative is Node.js, which is both free and Open Source. Other great apps like vert.x are asyncoro (Free, Open Source) and NoPrint.js (Free, Open Source).
asyncoro is a Python framework for developing concurrent, distributed programs with asynchronous completions and coroutines. Asynchronous completions implemented in asyncoro are socket I/O operations (non-blocking sockets), database cursors, sleep timers and locking primitives.
NoPrint.js is a small and neat open source JS library that disables print, screenshot, copy and paste functions in HTML. You can also enable the AutoBlur option to let the content turn to blur once the mouse leaves the webpage.