High performance side seal strapping machine for boxes or pallet loads. Can be integrated into conveyor line. Strapping head is side mounted on the arch and movable. During the strapping cycle, the strapping head indexes towards the load before tensioning sequence, so tensioning and sealing are done right against the side of the load. The bottom section of the strapping arch can be a standard undertrack style, or an electric motor driven pallet bayonet for "through-pallet" strapping, or a combination of both.