there isn't one, because that's not how the market works

it's like asking what's the world price for a tuna sandwich, there's a few million places you could buy one, and they all have a different price

Don't know about foremost, but I always use xe.com

Yeah, I was investigating transferwise because supposedly it was cheaper than xe.com but it seems like they are pretty competitive with each other. I've already been using xe.com and see no reason to switch.

I transfer my entire salary from USD to EUR every year so I definitely want to get the best rate.

I only use xe.com as my go to website for looking up current exchange spot rates. I didn't even really know they had a transfer service.

I am a very happy Transferwise user. I used to always check the exchange rate on xe.com, then switch to Transferwise to compare before transferring. Now I don't bother, because Transferwise has always been very close to the spot rate.

There is no foremost authority in foreign exchange, it's mostly an unregulated market.