I use a software that uses a Blockly interface (this is blockly), and this is the website where i build it.
The website gives you the option to program mods in either Blockly (which gets turned into JS, then translated into Java, and sent to their server so I can run it) or JS. It's really easy to use, but also very customizable.
Yeah I've used Notepad++ before. The software that I use translates blockly to JavaScript; so I don't really have to worry about the actual code, but I do have the option of looking at it.