If you're looking to find the cost to trade on various platforms, many platforms provide web pages with the pricing. Some of those pages are included, below. Keep in mind that pricing can vary between platforms, and even within a platform by user. That is, someone who trades frequently may have requested lower fees than stated on their website since they trade more often. Frequent traders can contact their broker to see if they can negotiate lower fees or other good-customer incentives.
Remember that commissions are not the only fees that traders will need to pay. Exchange fees are often passed through the broker to the customer, and may not be listed as part of their fees since they're just passing them through. Also, some platforms have licensing fees (e.g. NinjaTrader) to access all of the features of the platform, and NinjaTrader also requires its customer to pay for intraday data.
Keep in mind, too, the total cost of owning the platform, as one broker might charge more for commissions, but does not charge for data. To get the whole picture, you'll want to consider platform license fees, commissions, data fees, inactivity fees, support call fees, ACH fees, check fees, broker-assist fees, special product fees, margin rates, margin fees, margin call fees, interest rates, the lack of paying interest in your balance, etc..
|Platform||Link to stated fees||Notes (check vendor site for confirmation of any notes)|
|NinjaTrader||https://ninjatrader.com/Admin-Fees||NinjaTrader charges a license fee for full-featured access, as well as for data and also an inactivity fee if not trading at least monthly.|
|TDAmeritrade (thinkorswim)||https://www.tdameritrade.com/pricing.html||Does not charge for most data|
|TradeStation||https://www.tradestation.com/pricing/||Does not charge for most data, $0 base fee for many trade types|
Let John know if any of these links need updating, or if there's a link to add.