Jinx is a new product for writing Excel Add-Ins in Java: https://exceljava.com

It works by embedding the JVM in Excel and exposing annotated Java (or Scala, Kotlin etc) methods to Excel as UDFs.

You can download the current beta version for free: https://exceljava.com/download.html.

I'd be interested to hear any feedback you might have! If you have any problems getting started please let me know and I will help you.

It's intended that when out of beta it will be free to use for personal/non-commercial use.