A collapsible tree visualization displays hierarchical data as an interactive diagram with rectangular nodes representing structs and their fields. The example renders JSON data describing payment processing structures, with clickable nodes expanding or collapsing child elements. Built with D3.js v3 and React, the visualization uses SVG for rendering, featuring smooth animations during node transitions, color-coded elements, and tooltips that appear on hover. The tree layout supports zooming and dragging gestures, while links between nodes are highlighted when selected.