I know IB does, but because of the proliferation of HFT bots, I am assuming all broker have them just not all avail to retail traders.
We offer Lightspeed Trader, Sterling Trader Pro, Eze EMS (formerly RealTick), and CBOE Silexx which all have APIs. https://www.lightspeed.com/technology/trading-software/
There’s no reason a broker has to have an API if they’re not serving HFT, which most retail brokers do not. However, you can automate most brokers using the private API that their mobile app uses or by screen scraping their website.
I disagree. I don't do HFT, but find IB's API extremely useful. It's the main reason that I am with IB over TD.
Brokers with API (that we at MT connect to): TD Ameritrade, Webull, Ally Invest, Interactive Brokers, Tradier, Robinhood (not official), E*Trade (no streaming market data), Rithmic, Gain Capital, Questrade (Canada)
As far as i've had an experience, all forex brokers i've traded with had API's including Fxview, Forex.com, FXCM, XM. Though their minimum deposit is a bit much. But i think it is offered to retail as well.
You may consider including alpaca, another commission free api. One of my concerns of using third party software to connect to other brokers is that the third party software would have access to all my trade records. The reason I want to use multiple brokers is that no single broker knows what I am doing, but if the third party knows all my records, I would rather stick to one broker.
All communication in MT (I can't speak for other third party software) is directly between MT software running on your computer and the brokerage. It does not go through any middleman servers. We have thousands of users, quite a few just as (justifiably, I guess) paranoid as you. If we did any kind of underhanded stuff we would not have been able to stay in business for 20+ years.