To cite mongolite in publications use:

  Ooms J (2014). “The jsonlite Package: A Practical and Consistent
  Mapping Between JSON Data and R Objects.” _arXiv:1403.2805
  [stat.CO]_. <https://arxiv.org/abs/1403.2805>.

A BibTeX entry for LaTeX users is

  @Article{,
    title = {The jsonlite Package: A Practical and Consistent Mapping Between JSON Data and R Objects},
    author = {Jeroen Ooms},
    journal = {arXiv:1403.2805 [stat.CO]},
    year = {2014},
    url = {https://arxiv.org/abs/1403.2805},
  }