There are a lot of websites out there that will help you arbitrage Bitcoins and many other crytocurrencies alt coins. However it just a reference to help you manually arbitrage or use your local programs software apps to do your automated arbitraging.
Very helpful reference for arbitrage bitcoins and other altcoins. https://www.tokenspread.com/
It is highly recommend that you don’t share your API key secret to anyone, to any platform, to any remote program software. If you share or expose your API secret key, chances are mostly likely it will be use to take control of your account seeing your balance, transaction history, and possible to do withdrawal of your balance. In other word, if anyone have your secret API key of your Exchange account like coinbase poloniex bittrex … they can withdraw your coins empty your account, it is a big possibility that will happen when your API secret key is exposed.
So if you want to arbitrage. It is best that you don’t share your API key to non-trusted website or any remote website at all. To be safe, run a local program on your computer, so call trading bot locally, and arbitrage locally from your computer, it is the safest unless your computer get hacked but that’s a different story.