bt is a flexible backtesting framework for Python that uses a tree-based strategy composition model.

Instead of writing monolithic scripts, you build strategies as reusable building blocks:

• Strategy trees: combine, stack, and reweight sub-strategies

• 100+ built-in indicators and signals

• Multi-asset, multi-currency support

• Transaction cost modeling

• Detailed performance analytics (tearsheets, drawdown analysis)

• Integration with pandas, numpy, scipy

If you've ever struggled to backtest a portfolio of strategies — not just a single instrument — this is the tool.