httr
httr: a friendly http package for R
...-level SSL certificate store is used. Requests return a standard reponse object that captures the http status line, headers and body, along with other useful information. Support for OAuth 1.0 and 2.0 with oauth1.0_token() and oauth2.0_token(). The demo directory has eight OAuth demos: four for 1.0 (twitter, vimeo, withings and yahoo) and four for 2.0 (facebook, github, google, linkedin). OAuth credentials are automatically cached within a project.