LS TRader, Sterling Trader Pro, Realtick and Silexx all offer APIs. The only material difference in rates occurs with the per share rate on Realtick. As RT charges us a fee, we can't go as low. This does not affect per trade rates. On LST and Sterling, the default is to turn off MD to the display to avoid non-display fees. https://www.lightspeed.com/pricing/commission/
I do not know what broker route we use. We do not own our own. Might be ML, Barclay, CS etc. We use many and each route and platfrom can use a different broker route. I can tell you the number one place I add new accounts from is IB. I get no complaints about speed or executions quality. THese are not routes like TD where it sit with a BD like NITE or Citadel. The orders get posted to the ECN you target.
I don't think you should care too much about where your order is routed ... are you trying to get quick fill or cheap flll? Either way your order will interact with HFT. If you trade via internet, you are in no better position either way, imo.
It is interesting to view markets during times of system issues and flash crashes. HF MM widen their markets and what is left are a small number of customer orders. Sometime stocks go from 2 cents wide to 8 points wide. No way to avoid them unless you use a dark pools. We have those too but I would not bother. I would focus on my strategy and entry/exit points.
I'm using IB and doing around 2mm shares a month. my average total fee is around 0.0037 per share. this is assuming: IB commission: blended around 0.0022 per share exchange fee: 0.001 per share on average (for market on close) transaction fee: 0.000013 of total proceeds (for sales orders only) finra trading activity fee: 0.000119 per share (for sales orders only) Misc others: makes up the rest... ANY WAY TO REDUCE THIS? i use a lot of market-on-close orders...this is bring my total fees up a lot. the sales transaction fee also adds up to a pretty penny.