Nucleosides and their analogs are central to the biological and chemical sciences, as they serve a variety of biological functions and represent a growing class of anti-cancer and anti-viral pharmaceuticals. Although the synthesis of nucleosides typically proceeds via N-glycosylation of nucleobases with heavily protected sugar synthons, there is an increasing recognition for the inefficiency of the associated synthetic routes. Consequently, recent years have experienced renewed interest in the biocatalytic synthesis of natural and modified nucleosides. This includes, for instance, the enzymatic preparation of halogenated purine nucleoside synthons, the diversification of alkylated pyrimidine nucleoside analogues, the development of high-yielding flow processes, and the synthesis of the pharmaceuticals islatravir (anti-HIV) and molnupiravir (anti-Covid19) in biocatalytic cascades. All these examples employ nucleoside phosphorylases for key (trans-)glycosylation reactions, which enable the installation of ribosyl-based moieties on pyrimidine and purine nucleobases in one step and without the need for any protecting group chemistry.