This is a simple GUI Swing-based app which can help you to keep track of important dates. It is based on TSV-files, it allows import, export, autostart (Windows only), various date sorting methods, i18n, UI scaling.
Basic use case: run it by double-clicking .jar file, add important dates, export them via Export menu (as backup copy), check "Autostart" item in File menu, minimize window.
You will need Maven to compile, package and run it.
git clone https://github.com/Podbrushkin/date-manager-2.git
cd date-manager-2
mvn clean package
target\DateManager.jar
Or execute mvn clean compile exec:java to run it without packaging to jar. Autostart function wouldn't be available.