Most "house" platforms are free. They are designed or white labeled by the IB or FCM. I have found that most house platforms are inferior to 3rd party platforms. Usually you get what you pay for. #rd party platforms usually cost more because they are more dynamic, have more features and have more reliablity. Reason is that they are platform developers ONLY, not brokers. They are constantly updated and maximizing their product where house brokers usually are behind the curve. X trader, trademaven, strategy runner, ninjatrader, these are all 3rd party top of the line platforms that have fees but usually are better and more reliable than house platforms. Hope that answers your question
Some add it into the commissions. Some have cheaper fees because itâs non S7 traders using it. Some use outside vendors and some have there own technology which might be less. it could be a number of reasons why.