Trellis A framework-agnostic UI library for fractal, dockable workspaces in web apps. Panels nest to any depth, stay mounted when they dock, tab, or float, and users zoom into the area they are working on. The core is about 33kB gzipped with zero runtime dependencies, usable from React, a custom element, or plain DOM. Layouts serialize to one JSON document, theming uses CSS tokens, and it is free for non-commercial use with commercial licenses via GitHub Sponsors.