libcurl: libcurl-devel (rpm) or
libcurl4-openssl-dev (deb).

https://jeroen.cran.dev/curl (docs)
https://github.com/jeroen/curl#readme (devel)
https://curl.haxx.se/libcurl/ (upstream)

spelling, testthat (>= 1.0.0), knitr, jsonlite, rmarkdown,
magrittr, httpuv (>= 1.4.4), webutils

Jeroen Ooms [aut, cre] (<https://orcid.org/0000-0002-4035-0289>),
  Hadley Wickham [ctb],
  RStudio [cph]

c(
    person("Hadley", "Wickham", , "hadley@rstudio.com", role = "aut"),
    person("Jim", "Hester", , "jim.hester@rstudio.com", role = c("aut", "cre")),
    person("Kirill", "Müller", , "krlmlr+r@mailbox.org", role = "aut"),
    person("Daniel", "Cook", , "danielecook@gmail.com", role = "aut"))

Cache the results of a function so that when you call it
    again with the same arguments it returns the pre-computed value.

Hadley Wickham [aut],
  Jim Hester [aut, cre],
  Kirill Müller [aut],
  Daniel Cook [aut]

c(person("Baptiste", "Auguie",
    email = "baptiste.auguie@gmail.com",
    role = c("aut", "cre")), person("Anton", "Antonov",
    email = "tonytonov@gmail.com",
    role = c("ctb")))

Miscellaneous Functions for "Grid" Graphics

Provides a number of user-level functions to work with "grid"
    graphics, notably to arrange multiple grid-based plots on a page, and draw
    tables.

gtable, grid, grDevices, graphics, utils

Baptiste Auguie [aut, cre],
  Anton Antonov [ctb]

Create Elegant Data Visualisations Using the Grammar of Graphics

A system for 'declaratively' creating graphics,
    based on "The Grammar of Graphics". You provide the data, tell 'ggplot2'
    how to map variables to aesthetics, what graphical primitives to use,
    and it takes care of the details.

c(
    person("Hadley", "Wickham", , "hadley@rstudio.com", "aut",
           comment = c(ORCID = "0000-0003-4757-117X")),
    person("Winston", "Chang", , role = "aut",
           comment = c(ORCID = "0000-0002-1576-2126")),
    person("Lionel", "Henry", , role = "aut"),
    person("Thomas Lin", "Pedersen", , "thomas.pedersen@rstudio.com", 
           role = c("aut", "cre"), comment = c(ORCID = "0000-0002-5147-4711")),
    person("Kohske", "Takahashi", role = "aut"),
    person("Claus", "Wilke", role = "aut",
           comment = c(ORCID = "0000-0002-7470-9261")),
    person("Kara", "Woo", role = "aut",
           comment = c(ORCID = "0000-0002-5125-4188")),
    person("Hiroaki", "Yutani", role = "aut",
           comment = c(ORCID = "0000-0002-3385-7233")),
    person("Dewey", "Dunnington", role = "aut",
           comment = c(ORCID = "0000-0002-9415-4582")),
    person("RStudio", role = c("cph", "fnd"))
    )