Where can I get the benchmark interest rate of individual currencies? From there, one can calculate the interest rate differentials of various forex pairs to be traded. Thanks.
You can get current and historical forex daily swap rates at this Oanda page: https://www.oanda.com/forex-trading/analysis/historical-rates Oanda shows a bid and ask, which kick in depending on whether you are paying or receiving the rate. If you want a single benchmark rate, take the mid. You can also get these rates via an http get call to the free* V2 api. *free but may require an account. But since there is no minimum to open an account it is essentiall free.
I think you can use the interest rate tool from any finance platform. Here is one: https://www.forexchief.com/analytics/interest-rates/