This was taken from their FAQ page... you can find it here.
https://cryptrader.com/FAQQ: Is it safe to trade through this website? Does using it give CrypTrader access to my funds?
A:
Using API keys with permissions on a browser based trading platform is by far the safest way to trade. It does not give anyone including CrypTrader access to your funds.
API keys allow you to only execute trades, retrieve a balance, and get trade history as well as open order status. If an attacker gained access to your CrypTrader account, the worst they could do is trade for you. API keys ensure that your funds can not be withdrawn and are locked safely in the exchange.
Trading directly on the exchange's website exposes you to all sorts of threats from attackers such as cross server scripting attacks as well as phishing attempts using imitation pages ect. If an attacker gains access to your exchange account, withdrawal of your funds may be possible. Staying logged out of exchanges is a good idea when browsing around the web.
With a downloadable program you expose yourself to all sorts of threats on your local machine. Programs / executables can install keyloggers, steal wallet files, or change copied bitcoin addresses in your clipboard, and much more.
By using CrypTrader, you can rest assured that nobody will be able to access your exchange accounts and it creates the perfect barrier to block attackers from gaining access to your funds.