Like others here, I like Think or Swim by TD Ameritrade.

Just one problem though, in times of extreme market volatility and volume, Thinkorswim freezes up. Like today, it was unusable at times.

was that limited to ToS though? Wasn't much liquidity out there

Interactive Brokers and Tradestation didnt have much issues, but yes, getting filled on trades, especially options trades was a nightmare.

I was wondering about this, so Interactive Brokers was still pretty solid during last Mondays market swings?