The Quandl R package is an API wrapper around the NASDAQ Data Link Quandl API.
The R package is available on CRAN and GitHub.
Find the API Documentation online at https://docs.data.nasdaq.com/.
The current Rate Limits specify a limit of no more than 20 calls per 10 minutes and 50 calls a day for anonymous users.
Users who do not subscribe to any premium data but append their API key to their API call have a limit of 300 calls per 10 seconds, 2,000 calls per 10 minutes, and 50,000 calls per day.
Authenticated users have a concurrency limit of one, that is, they can make one call at a time and have an additional call in the queue.
Find your personal API on your account page: https://data.nasdaq.com/account/api.
Search for the freely available data sets at https://data.nasdaq.com/search?filters=%5B%22Free%22%5D.
All available tools to connect to the API are listed under https://data.nasdaq.com/tools/full-list.
Note that the Quandl R package differentiates between arguments that are specific to the R function and Nasdaq Data Link API query parameters that enter the R function as additional arguments. Click here for a full list of query parameter options.
Raymond McTaggart, Gergely Daroczi, Clement Leung (2021). Quandl: API Wrapper for Quandl.com. R package version 2.11.0, https://CRAN.R-project.org/package=Quandl.