I'm the CTO of BitMEX.com[1], which runs derivatives (futures and perpetual swaps) on Bitcoin and a few other coins. We've been around since 2014. We run a full-featured testnet [2] for API testing & trade testing.
The other major players are mostly Chinese. In China, there's OKCoin, BTCC (previously BTC China), 796, and BitVC, as well as a few minor players. In the rest of the world, there's us, CryptoFacilities, Coinpit, and now Deribit.
We've been in contract with the Deribit team since 2014 - they appear to be a solid tech team and they certainly understand the underlying finance.
In all earnesty, do you have an interest in your clients making big profits? Or is it in your best interest that most of your clients lose so that you can pay a few winners?
Do you have a training program that can help me go from 0 to full-time derivatives trader?