I'm new to this field. Besides backtesting.py, what other widely used and useful libraries are available for developing and testing algorithmic trading strategies?

[phi999]

i know there is a lot of them, but what you guys like to use the most and why?

[calmintp]

i particularly like using Nautilus Trader. It's an actively maintained project and provides a complete platform, all free.
Libs like this one or PyBroker, FastQuant and BackTrader, etc, are easier to start with and are manly focused on backtesting, but not frequently updated. Because of that, you often need to implement new features and fixes youreself.