Hi Achint,

Welcome to QuickBooks Community!

You can use any latest and reliable website available on the internet as a reference for foreign currency exchange rates. We don't have a recommendation as such. 

I hope this helps!

@Achint-Gupta ,

If you deal with multi-currency transaction, consider this service to accept your payment in local currency.

https://veem.grsm.io/veems

Hope it helps.