Embodiments of a closed-contact electroplating cup assembly that may be rapidly cleaned while an electroplating system is on-line are disclosed. One disclosed embodiment comprises a cup assembly and a cone assembly, wherein the cup assembly comprises a cup bottom comprising an opening, a seal surrounding the opening, an electrical contact structure comprising a plurality of electrical contacts disposed around the opening, and an interior cup side that is tapered inwardly in along an axial direction of the cup from a cup top toward the cup bottom.