Installing required library
install.packages("rjson")
library("rjson")
Using it
Creating the file (downloaded from somewhere) and assing the name to a value and read it with readChar
f <- '/tmp/pin.json'
j <- readChar(f,file.info(f)$size)
after that you can use this string object for the library
fromJSON(j)
x <- fromJSON(json)
resulting in a list object