Using data from Interactive Brokers, IBorrowDesk allows users to track live and historical fee rates and availability for shorting stocks. Well over 10k securities are currently in the database with daily data going back to when I began logging in July 2015. Real-time data is available in 15min intervals for the last week.
Registered users can keep a watchlist of securities and receive a morning summary with the latest data.
I also created a Twitter bot @IBorrowDesk as a fun side-project and marketing vehicle. Anyone can access current data by tweeting @ the bot with tickers and receive the latest data.