This package implements continuous-time hidden Markov models (HMMs) to infer identity-by-descent (IBD) segments shared by two individuals from their single-nucleotide polymorphism (SNP) genotypes. Provides posterior probabilities at each marker (forward-backward algorithm), prediction of IBD segments (Viterbi algorithm), and functions for visualising results. Supports both autosomal data and X-chromosomal data. The current model has two states, non-IBD and IBD1, and is intended for unilineal relationships. The methodology and package are described in Vigeland et al. (2026) <doi:10.1016/j.fsigen.2025.103409>.