The **diagram‑js** library is a lightweight, extensible toolbox for rendering and editing graphical diagrams directly in the browser. It provides core services (canvas, interaction, event handling, modeling, etc.) as ES modules that can be bundled by tools like Webpack or Rollup, and is used as the foundation for several web‑based modelers such as bpmn‑js, cmmn‑js, and dmn‑js, as well as custom diagram editors. It is aimed at developers building web applications that need interactive diagram viewing or authoring capabilities.