Spline is a 3D design and animation tool for designers, web developers, and creative agencies that combines real-time collaborative 3D modeling, animation, interaction design, and AR-ready output into a browser-based design app for embedding interactive 3D scenes in websites and apps. Marketed as collaborative 3D design and animation software, Spline combines real-time multiplayer 3D modeling, animation timeline with keyframes, physics simulation including gravity and collisions, materials and lighting, interactive events and triggers, AR scene export, embedded 3D scenes for websites with HTML, integrations with Figma, Webflow, Framer, and major web design tools, dedicated web and macOS apps, plus a Spline Library of community 3D assets. Spline is a strong fit for designers adding 3D to portfolios, web developers embedding interactive scenes, and creative agencies producing immersive client experiences.