d3-flame-graph is a D3.js library for creating interactive flame graphs from hierarchical data. It follows the D3 chart pattern with a closure-based factory function that returns a configurable chart function. The library processes JSON input data representing call stacks or hierarchies and renders them as SVG flame graphs with features like zoom, search, tooltips, and click/hover handlers. It includes specialized color mappers for different profiling contexts (allocation, off-CPU, Node.js, differential) and a smart tooltip component that handles boundary conditions. The architecture is modular with separate concerns for color mapping, tooltip handling, and core layout logic.