The ulptkit toolkit computes cosmological power spectra within the Unified Lagrangian Perturbation Theory (ULPT) framework. It evaluates nonlinear matter power spectra and provides consistent calculations of galaxy–galaxy auto power spectra and galaxy–matter cross power spectra for large-scale structure and cosmology applications, using user-supplied linear power spectra from emulators or Boltzmann solvers. The package includes demonstration scripts that compare ULPT-based predictions with halo–halo auto and halo–matter cross power spectra generated by the Dark Emulator.