ZOVER provides an analytical tool for comparative analyses on the virome diversity of two host/vector groups. Firstly, two comparison-modes are available for users to conduct either an intra-host comparison (e.g., two different bats) or an inter-host comparison (e.g., one bat vs. one rodent). Secondly, users can customize two host/vector groups at different taxonomic levels according to NCBI taxonomy. By default, the highest taxonomic level of user-customized hosts is allocated. Then, users who are interested in viruses identified in a particular period of time and/or geographic region may try the optional filters below to conduct any spatial/temporal comparative analyses.