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)

askpass, 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]

Stephan Wahlbrink, R binding based on the JavaGD package by Simon Urbanek

Graphics device implementation for RJSrv (package 'rj').
  The package can be used only when R was loaded via RJ.

Wrappers around the 'xml2' and 'httr' packages to make it easy to
    download, then manipulate, HTML and XML.

c(
    person("Hadley", "Wickham", , "hadley@rstudio.com", c("aut", "cre")),
    person("RStudio", role = "cph")
    )

testthat, knitr, png, stringi (>= 0.3.1), rmarkdown, covr

Helpers for Developing Command Line Interfaces

c(
    person("Gábor", "Csárdi", , "csardi.gabor@gmail.com", c("aut", "cre")),
    person("Hadley", "Wickham", role = c("ctb")),
    person("Kirill", "Müller", role = c("ctb"))
    )

A suite of tools to build attractive command line interfaces
    ('CLIs'), from semantic elements: headings, lists, alerts, paragraphs,
    etc. Supports custom themes via a 'CSS'-like language. It also contains a
    number of lower level 'CLI' elements: rules, boxes, trees, and
    'Unicode' symbols with 'ASCII' alternatives. It integrates with the
    'crayon' package to support 'ANSI' terminal colors.

assertthat, crayon (>= 1.3.4), glue, methods, utils, fansi

callr, covr, htmlwidgets, knitr, mockery, rmarkdown,
rstudioapi, prettycode (>= 1.1.0), testthat, withr

Gábor Csárdi [aut, cre],
  Hadley Wickham [ctb],
  Kirill Müller [ctb]

c(
    person("David", "Gohel", role = c("aut", "cre"),
    email = "david.gohel@ardata.fr"),
    person("Quentin", "Fazilleau", role = c("ctb"),
    email = "quentin.fazilleau@ardata.fr"),
    person("Maxim", "Nazarov", role = c("ctb"),
      comment = "rmarkdown for docx output"),
    person(given = "Titouan", family = "Robert", role = c("ctb")),
    person(given = "Michael", family = "Barrowman", role = c("ctb"), comment = "inline footnotes"),
    person(given = "Atsushi", family = "Yasumoto", role = c("ctb"), comment = "support for bookdown cross reference")
    )