Anyone using "Think or swim" broker

Anyone using “Think or swim” broker? I just downloaded their demo platform program with the intention for charting use and I admit it’s one of the good ones I come so far though definitely not newbie friendly like us. Heard the spread though is not that competitive as compared to Oanda. Is this broker a ECN or just another market maker?

they are market maker…I have account with them to trade futures and stock and options. their forex spread are steady.