AbstractSummaryTRviz is an open-source Python library for decomposing, encoding, aligning and visualizing tandem repeat (TR) sequences. TRviz takes a collection of alleles (TR containing sequences) and one or more motifs as input and generates a plot showing the motif composition of the TR sequences.Availability and implementationTRviz is an open-source Python library and freely available athttps://github.com/Jong-hun-Park/trviz. Detailed documentation is available athttps://trviz.readthedocs.io.Supplementary informationSupplementary dataare available atBioinformatics Advancesonline.