Plotly.js is a declarative JavaScript data visualization library built on D3 and WebGL that supports a wide range of statistical, scientific, financial, geographic, and 3-dimensional visualizations. Support for creating Plotly.js visualizations from Python is provided by the plotly.py library. Version 3 of plotly.py integrates ipywidgets support, providing a host of benefits to plotly.py users working in the Jupyter notebook. This paper describes the architecture of this new version of plotly.py, and presents examples of several of these benefits.