An expandable interbody spacer for spinal fusion includes opposing upper and lower end plates. An actuator moves the upper and lower end plates heightwise relative to one another to expand the height of the expandable interbody spacer. An end plate fastener secures the upper and lower end plates to one another and enables the upper and lower end plates to heightwise move relative to one another. The upper and lower end plates and the at least one end plate fastener are integrally formed as a single, one-piece, monolithic component. An expandable interbody space may include upper and lower end plates with overlapping anterior and posterior walls that define openings in communication with an internal chamber. An expandable interbody spacer may include a barrel nut defining a window to enable bone graft to pass therethrough and into an internal chamber.