I got fed up with all the spongebob/cursed(zalgo) text generators online being riddled with adverts so made my own. If anyone else wants to use it feel free, maybe give a tag back to the npm page or GitHub repo if you like it :D
If you're seeing a bunch of question marks or boxes (or question marks in boxes!) in your HTML after using curse you're probably just using a font that doesn't have the necessary diacritic symbols. I recommend font-family: "Arial, sans-serif"; as Arial seems to have everything supported and is available by default for most browsers.
I also don't recommend pushing the curse level above 10 if you still want the base text to be legible.