I use to use WorldCoinIndex for my portfolio but found some discrepancies. First, its cost average comes from all exchanges which with Asian markets being priced substantially higher its not a true reflection of your holdings.
I went on a venture looking for the best tracker. I came across CoinTracking but they ultimately are just trying to sell a subscription. Upon searching some more I found Cryptagon.
Use below link....
https://cryptagon.io/?i=C6RZ5P
It allows API connection to exchanges and soon will be able to link wallets too. An easy to use interface and its free.