This is a pure Java implementation of ZMQ.

https://github.com/zeromq/jeromq

Which means people can more effortlessly use in phone applications.

Also the Python ZMQ library is well established and works with Python 3.
That means people can use Python to create web applications, and also
servers that translate the ZMQ calls to Websockets (needed for third
party web applications).

Both of these look good for a client side library. Python 3 has
excellent async abilities and is very versatile, while Java is very
popular, especially on mobile.