Are you into trading? If you are, you can easily see how big their growth or dip in value in percentage. If you are not, yes you can go to coinmarketcap.com. There you can easily look for the coin you wish to know whether performing well or not. They have a little line graph beside the coin so you will see whether the direction is upward or not. Or if you really want to understand the coin more then Google the coin itself.