Group label work (ex. KJ method) is often used as an idea generation method. Group label work has been performed using papers such as sticky notes and a large paper sheet. However, using sticky notes has a drawback in terms of editing, managing and storage of working outcomes, and it is also difficult to digitize. Similar softwares and tools that help group label work have been proposed, but most of the tools depend on the specific platforms/operating systems. Therefore, we have developed a collaborative group label work system based on standard web technologies. By adopting the standard web technologies, the system works on multiple heterogeneous devices including PCs, tables, and smart phones as a web application. In this paper, we describe the design and implementation of the method. We also compared the proposed method and the system with conventional paper-based group label work in terms of creativity and efficiency.