B2R provides an R interface to some of the functionality in the Backblaze B2 API. Not all of the API is supported: in particular, functions for uploading large files in parts are not implemented. B2R contains functions for listing buckets and files, downloading files, and uploading files.
See Phill Clarke's backblazer
(CRAN, Github) for an existing package with bindings to the Backblaze B2 API.