Backend server (order management & execution) coded in C#, .Net Core.
Front end developed using Vue Js.
I am using AliceBlue API. Also have written wrappers for few other broker APIs. Coded Robo based order execution if broker does not support the API (though it is slow & error prone, frequent maintainance required, always prefer to go with API based approach, but kept as backup)
Using this tool, I can execute orders with multple brokers and see the combined PnL in realtime. Can mix match different strategies across various expiries & brokers. Allows adjusting executed strategies which are in danger and see the expected P/L visually on the payoff.
All are option strategies. Still adding new features whenever I get new ideas.