Gemini 
Gemini is an American-based crypto exchange, which is available in over 50 countries. It shows you how much each cryptocurrency asset has gained in dollars and percentages every day, which is great for trading.
Gemini has a seamless user experience and a good crypto referral program. All you need to do is invite a friend by copying and sharing your link.
Payout: Two business days.
What you get: $10 in BTC when your friends make a crypto trade within a month.
What your friend needs to do: Sign up and make a trade worth 100 USD in 30 days.
What your friends get: Same $10 in BTC.