A rope-climbing device has an upper assembly with planar side plates spaced apart by a roller, such that the side plates rotate relative to one another about a roller axis, a spine unit comprising planar links of common width each of half the plate spacing, the links pivoted at a central point, and a lower assembly comprising third and fourth side plates spaced apart by a clamp element such that the third and fourth side plates are enabled to rotate relative to one another about the clamp axis, and the clamp element is enabled to clamp a rope between the plates. The device may be opened by aligning pivot points, a rope inserted, and closed on the rope. Engaged on the rope, the device may be set to slide on the rope, or clamp to the rope by action of a user.