ECN/STP brokers all use an A-Book business model, they are intermediaries that send their clients' trading orders directly to liquidity providers or multilateral trading facilities (MTFs). These forex brokers make money by increasing the spread or by charging commissions on the volume of orders. Therefore, there are no conflicts of interest, these brokers earn the same amount of money with both winning and losing traders.
This type of forex broker is becoming increasingly popular because forex traders are reassured by the absence of this conflict of interest, as well as the fact that these brokers have an incentive to have profitable traders since they will increase their trading volumes and therefore the brokers' profits.