Communications platform that puts data protection first (alternative to Gitter.im and Slack).

Notification infrastructure for developers.

Platform for secure collaboration across the entire software development lifecycle, can be integrated with Gitlab (alternative to Slack).

Push notifications to phone or desktop using HTTP PUT/POST, with Android app, CLI and web app, similar to Pushover and Gotify.

Customer communication platform (alternative to Intercom and Zendesk).

Zulip is a powerful, open source group chat application.

Apprise allows you to send a notification to almost all of the most popular notification services available to us today such as: Telegram, Discord, Slack, Amazon SNS, Gotify, etc.

Notification server with Android and CLI clients (alternative to PushBullet).

Instant messaging platform. Backend in Go. Clients: Swift iOS, Java Android, JS webapp, scriptable command line; chatbots.

Fully-featured Matrix client for Web, iOS & Android.

The most private and secure chat and applications platform - now with double ratchet E2E encryption.

Screego is a simple tool to quickly share your screen to one or multiple people via web browser.

Language-agnostic real-time messaging (Websocket or SockJS) server.

Conversational app builder (alternative to Typeform and Landbot).

Low-latency, high quality voice/text chat software.

Virtual office / virtual conference application presented as a 16-bit RPG video game.

Server for [Matrix](https://matrix.org/), an open standard for decentralized persistent communication.

Next generation noIM application in your own workspace, not only another Slack/Discord/rocket.chat.

Share sensitive information securely with self-destructing links that are only viewable once.

Distributed, secure messenger with audio and video chat capabilities.

Web Whiteboard to collaborate in real-time on schemas, drawings, and notes.

Stoat is a user-first chat platform built with modern web technologies.

Realtime server for reliable two-way communication over WebSockets, Server-sent events, etc.

Peer-to-peer chat app that is serverless, decentralized, and ephemeral.

Live Support chat for your website.

Secured and decentralized communication system. Offers decentralized chat, forums, messaging, file transfer.

High-performance and feature-rich chat server for Matrix, and the successor to conduwuit (fork of Conduit).

Whistleblowing software enabling anyone to easily set up and maintain a secure reporting platform.

Federated, end-to-end encrypted messaging service for the web, iOS, and Android, supporting text, photos, video, and WebRTC video and audio calls.

Anonymously share files, browse and publish _freesites_ (web sites accessible only through Hyphanet) and chat on forums.

A simple, fast, and reliable chat server powered by Matrix.

Multichannel notification server with support for Email, Mobile Push, Web Push, SMS, messaging and a javascript plugin.

One-Time-Secret sharing platform with a symmetric 256bit AES encryption in the browser.

Keep secrets out of emails or chat logs, share them using secure links with passphrase and expiration dates.

Spectrum 2 is an open source instant messaging transport. It allows users to chat together even when they are using different IM networks.

Notification server for relaying push notifications via Matrix, similar to PushBullet and Gotify.

All-in-one customer engagement platform from lead-gen to post-sales, from WhatsApp to your website. With omni-channel live agents and AI-powered chatbots (alternative to Intercom, Zendesk, Tawk.to and Tidio).

Next-Gen self-hosted chat server and clients.

Software framework for decentralized, peer-to-peer networking.

Online whiteboard, audio/video conferencing, screen sharing, shared code editing and optional session recording/playback.

Universal communication platform which preserves the user's privacy and freedoms.

Alternative private mail system - web-based, end-to-end encrypted by design, self-hosted, decentralized, uses independent PKI. Easy to install and administrate, freeware, open-source.

Platform for your corporate communications, based on the advanced architecture, with support for UltraHD video conferencing, built-in messenger with personal and group chats, and a free version for up to 1,000 users.

Instant messaging and collaboration tool with private and group chat rooms, continuous voice and video meetings, files sharing, issue tracking with integrated task board (alternative to Slack).