The R-SIG-Finance email list has a thread "Free financial data - equities, equity options and ETFs - for quantmod package (or other packages)" where the following sources are discussed: Yahoo Finance https://finance.yahoo.com/ https://eodhistoricaldata.com/ Tiingo https://www.tiingo.com/welcome Quantgo https://www.quantgo.com/ IEX https://iextrading.com/trading/market-data/ Barchart https://www.barchart.com Quandl https://www.quandl.com/ iqFeed https://www.iqfeed.net/index.cfm Interactive Brokers (with brokerage account) https://www.interactivebrokers.com/en/home.php ActiveTick https://www.activetick.com/activetick/contents/ IEX https://iextrading.com/trading/market-data/ Barchart https://www.barchart.com polygon.io https://polygon.io/stocks TradingPhysics http://www.tradingphysics.com/Feeds/AvailableFeeds.aspx