The artifact is built around the MultiselectJS library that implements the multi-selection semantics presented in the companion paper. The purpose of this JavaScript library is to help programmers add multi-selection to Web user interfaces with ease. The artifact includes a demo application showcasing the use of the library, documentation of the library API, and a tutorial on how to use the library. The library clearly separates the reusable aspects of multi-selection from the application specific aspects. The latter are collected into an object referred to as the selection geometry. The complex task of implementing a full-fledged multi-selection feature reduces to a considerably simpler task of implementing a selection geometry. The demo application implements several different selection geometries. It supports the claims of the companion paper that the library considerably lessens the task of implementing multi-selection. Following the guidance of the tutorial, users can build their own multi-selection features.