  We present the PSALTer software for efficiently computing the mass and energy
of the particle spectrum for any (e.g. higher-rank) tensor field theory in the
Wolfram Language. The user must provide a Lagrangian density which is expanded
quadratically in the fields around a Minkowski vacuum, is linear in the
coupling coefficients, and otherwise built from the partial derivative and
Minkowski metric. PSALTer automatically computes the spin-projection operators,
saturated propagator, bare masses, residues of massive and massless poles and
overall unitarity conditions in terms of the coupling coefficients. The
constraints on the source currents and total number of gauge symmetries are
produced as a by-product. We provide examples from scalar, vector, tensor and
gauge theories of gravity. Each example, including spectra of higher-spin
modified gravity theories, may be obtained on a personal computer in a matter
of minutes. The software is also parallelised for use on high-performance
computing resources. The initial release allows for parity-preserving operators
constructed from fields of up to rank three: this functionality will be
extended in future versions. PSALTer is a contribution to the xAct project.
