cattaDoc is web/cloud-based: The user needs a browser. The rest is on the backend server.
All the user needs is a web browser and a URL - a web address - for cattaDoc. The user interface is browser-based and no other installation is required in order to run cattaDoc.
The previous issues - ie. before cattaDoc version 5 - with certain browsers, especially Internet Explorer, has hopefully been eliminated by using Bootstrap and JQuery.