taxize is an R package that provides a unified programming interface to dozens of biodiversity and taxonomic web services. It resolves scientific names against sources such as ITIS, NCBI Taxonomy, GBIF, WoRMS, BOLD, EOL, Tropicos, IUCN, POWO, and Index Fungorum; retrieves stable identifiers; and fetches classifications, synonyms, children, downstream taxa, common names, and taxonomic ranks. The package is primarily a client library rather than a data pipeline, although it ships several small reference datasets and vignettes that support ecological and evolutionary research workflows. The architecture is built around S3 generics (classification, downstream, synonyms, children, sci2comm) and typed identifier classes (tsn, uid, gbifid, wormsid, etc.), with each get_* function returning a vector carrying match metadata and a URI. A shared HTTP layer built on crul handles requests, API-key injection, and error handling, while R6 classes track batch progress and interactive disambiguation.