I have been looking at the cTrader Spotware platform as it recently have been made possible to trade indices on the platform. According to IC Markets scalping is allowed as there is no restriction on trading, this comes with extremly fast execution and ultra low latency at their servers in LD5 IBX Equinix Data Centre in London.
http://www.icmarkets.com/forex-trading-platform/ctrader/
http://www.icmarkets.com/forex-trading-platform/ctrader/