Spritesmith is a Node.js library that takes a collection of image files and packs them into a single spritesheet, outputting the combined image (as a Buffer or stream) together with a JSON‑style map of each sprite’s x/y coordinates and dimensions. It’s aimed at front‑end developers and build‑tool authors who need to generate CSS‑friendly sprite assets, and is available as a core module, CLI, and plugins for Grunt and Gulp.