Certificates of Deposit

I have some “chicken money” and want to find the online institution with the highest CD interest rate. Every one I’m interested in shows a very high percent on their website, but when I call them to confirm, it’s ALWAYS a much lower percent when I tell them my zip code. It doesn’t seem fair their website doesn’t say in fine print it changes by zip code! Now it’s impossible for me to find the highest rate unless I call each and every institution, and I don’t have that time. But thank you for YOUR time!