Calculon is a basic, open-source, cross-platform, and “note-style” calculator inspired by Numi.
Calculon is written in Java and uses the exp4j library for evaluating the mathematical expressions. It’s developed with the Netbeans IDE and the Swing GUI Builder.
It is a very rudimentary implementation, just enough to solve around 80% of my problem, so it is not very polished right now and the code is far away from best practices.
Repository: github.com/sj14/calculon