Unless you use robinhood which has no transactions fees.
It's easy to have no fees if your customers can't make transactions.
To be less snarky, I'd avoid them if you're trying to time the markets.
"Please be aware that due to exceptional market volatility, there may be situations in which it is difficult to obtain a price for your trade."
Will be interesting to see what effect the Budget statement on Wednesday
Expect your orders to not execute as intended and money to be lost.
A free system gets you only so far