As you will watch this image below, it will provide you the link for seeing the FII Data on a daily basis which is through the reliable originator only. However, as a retail trader, you need not worry about the Fii data as they are not interested in retail trader actions. Many think that Fiis get their stop loss hit. Please understand that a retail trader is a small fry for the Foreign Institutional Investors (FIIs) and Domestic Institutional Investors (DIIs) and one should not take much cognisance from their actions.
If you are so worried, remember that you have to take trade-in scrip or Index which has a huge depth like Bank Nifty has a huge depth in Indian stock market and it is very rare that FIIs can get your stop loss hit by their deliberate action. Thus retail traders just chill and you can concentrate on your actions without worrying about FIIs data every day.