ATON is an advanced, modular framework developed by CNR ISPC to support the creation of Web3D and WebXR applications—including 3D presenters, virtual tours, immersive analytics tools, and multi‑user collaborative environments. Built on modern web standards such as Node.js, Three.js, WebXR, glTF, and Cesium 3D Tiles, ATON enables the “develop once, deploy everywhere” paradigm, automatically adapting to desktops, mobile devices, museum kiosks, and VR headsets. Its powerful API supports real‑time semantic annotations, PBR rendering, multi‑resolution visualization of massive datasets, spatial UI elements for XR, and synchronous multi‑user features. Designed with cultural heritage in mind, ATON allows researchers to interact with complex 3D scenes directly in the browser, integrate multimedia content, manage scenes and viewpoints, and run immersive collaborative sessions, making it a highly flexible and scalable tool within digital heritage workflows.