Open-source alternatives to Slack

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

MIT · released 2026-09-01

Notification infrastructure for developers.

MIT · released 2026-09-07

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

⊘ Proprietary · released 2026-09-07

Customer communication platform (alternative to Intercom and Zendesk).

⊘ Proprietary · released 2026-08-27

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

Apache-2.0, GPL-2.0 · released 2026-08-27

Zulip is a powerful, open source group chat application.

Apache-2.0 · released 2026-08-10

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

AGPL-3.0 · released 2026-09-02

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.

MIT · released 2026-08-31

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

MIT · released 2026-08-27

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

GPL-3.0 · released 2026-07-04

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

Apache-2.0 · released 2026-09-01

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

MIT · released 2026-09-07

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

GPL-3.0 · released 2026-08-20

Conversational app builder (alternative to Typeform and Landbot).

AGPL-3.0 · released 2026-08-21

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

BSD-3-Clause · released 2026-07-19

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

AGPL-3.0, Commons-Clause · released 2026-09-04

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

Apache-2.0 · released 2026-09-02

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

MIT · released 2026-09-07

Distributed, secure messenger with audio and video chat capabilities.

GPL-3.0 · released 2025-01-27

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

AGPL-3.0 · released unknown

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

AGPL-3.0, MIT · released 2025-11-24

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

Apache-2.0 · released 2026-08-19

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

MIT · released 2026-08-06

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

GPL-2.0 · released unknown

Live Support chat for your website.

Apache-2.0 · released 2026-09-07

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

GPL-2.0 · released 2023-11-30

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

AGPL-3.0 · released 2026-07-26

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

Apache-2.0 · released 2024-06-20

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

GPL-2.0 · released 2026-09-04

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

Apache-2.0 · released 2026-02-12

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

MIT · released 2022-11-30

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

Apache-2.0 · released 2026-07-25

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

GPL-3.0 · released 2023-06-12

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

MIT · released 2026-01-22

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

ISC · released 2025-05-29

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).

MIT · released 2021-11-29

Next-Gen self-hosted chat server and clients.

GPL-3.0 · released 2026-07-07

Community-driven Matrix homeserver, the continuation of conduwuit focusing on user experience and new features (fork of Conduit).

Apache-2.0 · released unknown

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

GPL-3.0 · released unknown

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

⊘ Proprietary · released unknown

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

GPL-3.0 · released unknown

Web-based, end-to-end encrypted email platform that uses an independent PKI.

⊘ Proprietary · released unknown

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.

⊘ Proprietary · released unknown

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).

⊘ Proprietary · released unknown