Quantopian - Your algorithmic investing platform
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.
Backtrader - Backtrader is a complete and advanced python framework that is used for backtesting and trading.
quantra - A public API for quantitative finance made with Quantlib
CloudQuant - Crowd based algorithmic trading development and backtesing for stock market trading.
Streak.world - Streak.world is one of the leading algo trading platforms, allowing you to design an algorithm to automate your trading strategies without any coding skills needed.