Built with Spring Boot + Vanilla JS Use Java 8 or later version to test it.

1. IDE: it's a maven project so any modern Java IDE should be able to import it correctly. From the IDE run the CurrencyconverterApplication which is the entry point with the main method. I personally used Intellj for the development.
2. Maven: use mvn package to produce a jar in the target folder, then do java -jar target/currencyconverter-0.0.1-SNAPSHOT.jar to start the backend, check that localhost:8080/ responds with a simple instruction string.

Once the backend is running open in Chrome the static index.html in the frontend folder and that should display the app in Chrome.