STELA Toolkit is a fully documented Python package for interpolating gappy/irregular, noisy light curves using Gaussian Processes, enabling the computation of a wide range of time-domain and frequency-domain data products. STELA supports standard Fourier frequency-resolved products such as power spectra, cross spectra, lag spectra, and coherence, as well as lags via the Cross-Correlation Function (CCF), interpolated with GPs or traditional linear interpolation.