  We show that the boundary charge and spin can be used as alternative
signatures of the topological phase transition in topological models such as
semiconducting nanowires with strong Rashba spin-orbit interaction in the
presence of a magnetic field and in proximity to an $s$-wave superconductor. We
identify signatures of the topological phase transition that do not rely on the
presence of Majorana zero-energy modes and, thus, can serve as independent
probes of topological properties. The boundary spin component along the
magnetic field, obtained by summing contributions from all states below the
Fermi level, has a pronounced peak at the topological phase transition point.
Generally, such signatures can be observed at boundaries between topological
and trivial sections in nanowires and are stable against disorder.
