Lean algorithmic trading engine by QuantConnect
C# algorithmic trading platform
DataFrame server for financial timeseries data
Test Trading Strategies Using Real Market Data
A nimble options backtesting library for Python
C++ Trade Platform for quant developer
Open-source crypto currency exchange software
A Powerful Algorithmic Trading Gateway
Free Java components for Quantitative Finance and Algorithmic Trading
User-friendly and completely free algorithmic trading platform
Technical analysis + LLM powered trading workflows
Trading backtesting environment for training reinforcement learning
Zipline, a Pythonic algorithmic trading library
Algorithmic Trading solution
Testing framework for structures regarding performance.