I don't know what sources you are using to fetch Bitcoin prices but you should mention them somewhere (I couldn't find any info about that), and using multiple sources mid value would be the best option.

There is a lot of blank white space on your website so I would definitely make those numbers for BTC and fiat currencies bigger, and date font size should be smaller.

I like date and calendar feature but oldest date I can find for historic Bitcoin prices is September 2013, so adding prices before that would be great.