does haidong gumdo and kendo have belts

Does anyone know if haidong and kendo and kumdo have belts or just rankings

Kendo does not have special colored belts. The ranking system does included kyu ranks before dan ranks however. These would be roughly equivalent to colored belts before black. Once you reach 1st kyu(they count backwards, 1kyu would be the highest kyu rank), the next step is 1dan and the dan ranks go up from there. To my knowledge, and I'm not a Kendo student, there is no visible indication of rank.

I don't know anything at all about the korean arts.

Haidong Gumdo uses the same Kyu/Dan system. We just call them Gup and Dan.