Download JD-GUI to open JAR file and explore Java source code file (.class .java)
Click menu "File → Open File..." or just drag-and-drop the JAR file in the JD-GUI window erupt-tpl-ui.anims-editor-demo-1.12.9-springboot2.7.17-r1.jar file.
Once you open a JAR file, all the java classes in the JAR file will be displayed.
