This is an R interface for the Google QPX Express API. Still undergoing development and testing. Has not been tested on Windows or Mac yet. More documentation on the API can be found here.
devtools::install_github('rweyant/googleflights')
library(googleflights)
# Set API key in a place all the functions have access to
set_apikey(YOUR_APIKEY)
search(origin='DTW',dest='BCN',startDate='2015-11-27',returnDate='2015-12-11')