Converse.js is an instant messaging client for websites. It provides an entirely browser-based Jabber/XMPP interface, and can connect to any XMPP public server. Converse implementes single and multiuser chats, invitations, service discovery, direct registration, contact lists, roosters and vCard exchange, status changes and messages, typing and state notification, and OTR encryption.
Ricochet is a peer-to-peer, anonymous and secure instant messaging system utilizing Tor. It allows chatting with anyone without exposing an identity or IP address. It does not reveal any meta data, contacts, as it does not rely on central servers.
Cutegram is a user-friendly telegram client. And Telegram a mobile and desktop messaging service with open source clients atop proprietary server infrastructure. Cutegram is cross-platform and desktop compatible. It's based on Qt5, QML, libqtelegram, and appindicators, supports Twitter and Emoji.