Converse.js

Converse.js is an XMPP chat client that runs entirely in the browser. It can be used as a standalone web app or embedded in an existing website, and it connects to any XMPP server rather than depending on a central service. The project is released under the MPL-2.0 license and has been developed since 2012.

It offers several display modes: overlay chat boxes, a full-page application, and embedded components. Messaging features include message styling, corrections, reactions, URL previews, and HTTP file upload, and it supports end-to-end encryption through OMEMO, custom status messages, desktop notifications, and anonymous login where the server allows it. A plugin architecture lets developers extend it, and the interface is translated into more than 40 languages.

You can try the hosted app at conversejs.org, run your own instance, or use the Converse Desktop and Converse Tauri applications. It suits organizations that want to add chat to a site on an XMPP backend, and individuals who prefer open, federated messaging over proprietary chat platforms.