QuantConnect
Lean Algorithmic Trading Engine by QuantConnect (Python, C#)
StockSharp
Algorithmic trading and quantitative trading open source platform to develop trading robots (stock markets, forex, crypto, bitcoins, and options).
Lumiwealth
Backtesting and Trading Bots Made Easy for Crypto, Stocks, Options, Futures, FOREX and more. Lumibot also makes it very easy to run and backtest agentic AI trading strategies in a safer way.