Spline is a web-based, collaborative 3D design platform for creating production-ready interactive 2D and 3D experiences directly in the browser. Built for designers, developers, and creative teams, Spline combines real-time 3D modeling with a powerful AI toolkit that accelerates ideation from the very first prompt. Its Spline AI add-on powers AI 3D Generation, letting users describe an object in plain text or upload a 2D image to instantly produce up to four distinct 3D model variants, remix earlier creations, and build a personalized 3D asset library. Complementing this are AI Texture Generation and AI Style Transfer, which apply materials and visual styles to objects on demand. Beyond AI, Spline offers a full modeling suite with sculpting tools, boolean operations, parametric objects, a pen tool for custom paths, and shape blending, alongside a state-based interactivity system that handles hover effects, click triggers, scroll-driven animation, physics, and particles through a visual logic builder rather than code. The platform supports Gaussian Splat import for photorealistic captures, real-time variables wired to webhooks and APIs, and the Hana design suite for 2D collaborative canvases. Finished projects export to the web, iOS, Android, and production code, making Spline a go-to tool for interactive websites, product mockups, 3D logos, animated characters, and immersive brand experiences.