JupyterLab Visual Debugger and xeus‑python Kernel: Installation, Features, and Front‑End Architecture

JupyterLab now offers a visual debugger, enabling breakpoint setting, variable inspection, and execution control directly within notebooks, addressing the long‑standing lack of visual debugging in Jupyter.

To use it, install the front‑end extension with jupyter labextension install @jupyterlab/debugger and the back‑end kernel conda install xeus-python -c conda-forge , which implements the Jupyter Debug Protocol.

xeus‑python, the first kernel to support Jupyter debugging, provides a pluggable concurrency model and a lightweight codebase, making it suitable for building language kernels such as Python.

The debugger UI adds a side‑panel file explorer, source preview, call‑stack navigation, inline breakpoint toggles, and visual markers indicating the current execution point, plus variable browsers and tree/graph visualizations.

Demo GIFs show debugging of deleted cells, console debugging, multi‑notebook debugging, and variable inspection, while future plans include richer variable rendering and conditional breakpoints.

A related VS Code visual debugging tool is also highlighted, featuring real‑time data‑structure visualizations such as linked lists, trees, tables, and Plotly charts.

Additional resources and a QR code are provided for a free Python public course and related learning materials.