A shelf or storage rack includes a top defined by a pair of elongated members held at a spaced distance from one another by a pair of frame end members and at least two frame cross-members respectively disposed at a spaced distance from each of the pair of frame end members to define a plurality of spaced slots. A left side support and a right side support are each defined by elongated support members held by at least one support cross-member, wherein at least a portion of the elongated support members has a first end including a protrusion and an adjoining support ledge and an opposed second end including a notch or groove. The protrusions and notches or grooves interact to provide a vertically stackable modular shelf or storage rack system.