Three.js

Three.js is an open-source JavaScript library that renders 3D graphics in web browsers using [WebGL](/glossary/webgl). It abstracts away the complexity of the WebGL API, giving developers a high-level toolkit for building 3D scenes with cameras, lighting, materials, geometry, and animation loops. Originally created by Ricardo Cabello (Mr.doob) in 2010, Three.js has become the most widely adopted 3D library for the web, used in everything from product configurators and architectural walkthroughs to data visualizations and interactive storytelling. Because it runs on the GPU through WebGL, Three.js can render complex scenes at 60 frames per second on modern hardware without requiring plugins or native app installations.

Three.js makes high-fidelity 3D rendering possible inside an ordinary browser tab. For digital publishing, that capability is transformative. Instead of delivering flat images of printed pages, publishers can present content with physical depth, realistic lighting, and smooth animation. Readers interact with pages that curl, cast shadows, and respond to touch or mouse input, creating a tactile feel that static PDFs cannot replicate. The library works across all major browsers (Chrome, Firefox, Safari, Edge) and adapts to a wide range of devices, from high-end desktops to mid-range smartphones. This cross-platform reach means publishers can deliver a premium reading experience without restricting their audience to a specific app or operating system.

Three.js is the core rendering engine behind FlipLink's flipbook experience. When you upload a PDF and create a flipbook, FlipLink uses Three.js to render each page as a 3D surface with realistic [page-flip animations](/glossary/page-flip-animation). Every page turn is calculated in real time: the paper deforms along a curve, the underside of the page becomes visible, and dynamic shadows shift across the spread. The renderer supports different [cover types](/glossary/cover-type) — [hardcover](/glossary/hardcover) and [paperback](/glossary/paperback) — each with distinct bending behavior and spine mechanics. Three.js renders the entire scene using the reader's GPU, so animations stay smooth without server-side processing. FlipLink also offers a PDF.js-based [document viewer](/glossary/document-viewer) for situations where a simpler layout is preferred, letting publishers choose the right format per publication.