As viruses continue to pose risks to global health, having a better understanding of virus⁻host protein⁻protein interactions aids in the development of treatments and vaccines. Here, we introduce Viruses.STRING, a protein⁻protein interaction database specifically catering to virus⁻virus and virus⁻host interactions. This database combines evidence from experimental and text-mining channels to provide combined probabilities for interactions between viral and host proteins. The database contains 177,425 interactions between 239 viruses and 319 hosts. The database is publicly available at viruses.string-db.org, and the interaction data can also be accessed through the latest version of the Cytoscape STRING app.