Top Alternatives to Zulip

Skype is an instant messaging and VOIP (Voice Over Internet Protocol) client to communicate with people in a distant place.

Hangouts is an instant messaging software developed by Google.

Telegram is a free cloud-based instant messaging platform.

Slack is a cloud-based team collaboration tool.

Tox is a peer-to-peer instant-messaging and video-calling protocol that offers end-to-end encryption.

Trillian is a proprietary multiprotocol instant messaging application.

Viber Free Messenger and Phone Calls.

Discord is a freeware proprietary VoIP application designed for gaming communities.

Signal is the most scalable encryption tool.

Imo free video calls and chat is a kind of Communication apps for Android.

Facebook Messenger is the official Facebook app that lets you have text conversations with all of your friends on the popular social network.

Empathy is an instant messaging (IM) and voice over IP (VoIP) client which supports text, voice, video, file transfers, and inter-application communication over various IM protocols.

Glip is fully searchable, real-time group chat; video chat, task management, file sharing app.

LINE is a new communication app which allows you to make free voice calls and send free messages whenever and wherever you are.

Mattermost is an open source, private cloud Slack-alternative, Workplace messaging for web, PCs and phones. MIT-licensed.

Wire is a cross-platform, encrypted instant messaging client created by Wire Swiss. It is available for iOS, Android, Linux, Windows, macOS and Web browser clients.

ICQ is an open source instant messaging software.

WeChat is a social media with instant messaging, commerce and payment services application.

Rocket.Chat free open source chat solution.

ChatSecure is a messaging application for iOS which allows OTR and OMEMO encryption for the XMPP protocol.

Kik Messenger is an instant messenger software.

Handcent Next SMS a customizable and powerful SMS messenger app.

Instantbird is a cross-platform instant messaging client based on Mozillas XULRunner and the open source library libpurple used in Pidgin.

Xabber (XMPP and Jabber) is a XMPP client for the Android Operating System.

Threema is an encrypted instant messaging application for iOS, Android and Windows Phone.

Voxeet is VoIP web conferencing software that uses 3D high definition voice technology to produce immersive sound.

Matrix is an open protocol for real-time communication. It is designed to allow users with accounts at one communications service provider to communicate with users of a different service provider via online chat, Voice over IP, and Videotelephony.

Let's Chat is a persistent messaging application that runs on Node.js and MongoDB. It's designed to be easily deployable and fits well with small, intimate teams.

Tango is the messaging app with the best video calling. All messages and calls are free.

KakaoTalk (Korean: 카카오톡), or sometimes KaTalk, is a free mobile instant messaging application for smartphones with free text and free call features.

BlackBerry Messenger, also known as BBM is an instant messenger and videotelephony application included on BlackBerry devices that allows messaging and voice calls between BlackBerry, iOS, Android, and Windows Mobile users.

Conversations is an open source XMPP/Jabber client for the Android platform.

GO SMS Pro is a free app that replaces the stock SMS messaging interface for your Android device.

TribeScale is an All-in-One platform to coordinate your team around what really matters - communication, goals, decisions, tasks and results.

Flock is a communication app for teams. Packed with tons of productivity features, Flock drives efficiency and boosts speed of execution.

Zoiper is an easy to use sip video softphone, with excellent voice quality and easy to setup.

Sicher is a freeware instant messaging application for iOS, Android, and Windows Phone. Sicher allows users to exchange end-to-end encrypted text messages, media files and documents in both private and group chats.

Tencent QQ (QQ) is an instant messaging software service.

Talkatone is a free calling app.

GroupMe is a mobile group messaging app.

QuteCom (WengoPhone) is a free-software SIP-compliant VoIP client.

Disa is your new messaging hub. Conversations from different services can seamlessly be joined together, or disbanded within seconds.

Silence.im is an encrypted text messaging service.

Dialog Messenger is a handy and feature-rich enterprise multi-device messenger available for server or cloud.

Wickr is an instant messenger application.

Phoner and PhonerLite are softphone applications for Windows operating systems available as freeware.

Gitter is an open source instant messaging and chat room system for developers and users of GitHub repositories.

Hack Chat is a minimal, distraction-free chat application.

Tkabber is a GPL instant messaging client for the XMPP protocol which uses the Tk toolkit for the GUI.

Dasher Messenger provids a way to message friends.