Here is a free forex arbitrage monitor, which track about twenty forex brokers and compare their quotes in real time: http://www.forexbrokerz.com/forex-arbitrage
If 2 pip or larger difference is detected and that difference last for more than 1 sec, it will appear on the radar.
If 2 pip or larger difference is detected and that difference last for more than 1 sec, it will appear on the radar.