QuantConnect - QuantConnect provides a free algorithm backtesting tool and financial data so engineers can design algorithmic trading strategies. We are democratizing algorithm trading technology to empower investors.
Quantopian - Your algorithmic investing platform
quantra - A public API for quantitative finance made with Quantlib
Backtrader - Backtrader is a complete and advanced python framework that is used for backtesting and trading.
Intrinio - Intrinio is a trading platform, providing professionals with the best in class financial market data API and other tools.
Quantreex - An automated trading platform that you let you create trading strategies intuitively.