Token Holder Tab on Explorer
For every token on BNB, Ethereum and Arbitrum Explorer, you can see a 'Holders' tab that you gives you information on holders of the particular token including top holders, change in Gini, Nakamoto Indexes and total supply.
Click on Get API
at the bottom of each widget to get the corresponding query from the token holder API.
To read more about how to calculate Gini Coefficient, Nakamoto Index and Theil Index, go here