Software

Secured and decentralized communication system. Offers decentralized chat, forums, messaging, file transfer. ([Source Code](https://github.com/RetroShare/RetroShare))

Communications platform that puts data protection first (alternative to Gitter.im and Slack). ([Source Code](https://github.com/RocketChat/Rocket.Chat))

Next-Gen self-hosted chat server and clients. ([Demo](https://app.samacloud.io/demo), [Source Code](https://github.com/SAMA-Communications/sama-server), [Clients](https://github.com/SAMA-Communications/sama-client))

Simple tool to quickly share your screen to one or multiple people via web browser. ([Demo](https://app.screego.net/), [Source Code](https://github.com/screego/server))

Instant messaging transport. It allows users to chat together even when they are using different IM networks. ([Source Code](https://github.com/SpectrumIM/spectrum2))

User-first chat platform built with modern web technologies. ([Source Code](https://github.com/stoatchat/self-hosted))

Server for Matrix, an open standard for decentralized persistent communication. ([Source Code](https://github.com/element-hq/synapse))

Next generation noIM application in your own workspace, not only another Slack/Discord/rocket.chat. ([Demo](https://nightly.paw.msgbyte.com/), [Source Code](https://github.com/msgbyte/tailchat))

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). ([Source Code](https://github.com/Tiledesk/tiledesk))

Instant messaging platform. Backend in Go. Clients: Swift iOS, Java Android, JS webapp, scriptable command line; chatbots. ([Demo](https://sandbox.tinode.co/), [Source Code](https://github.com/tinode/chat), [Clients](https://github.com/tinode/webapp))

Distributed, secure messenger with audio and video chat capabilities. ([Source Code](https://github.com/TokTok/c-toxcore))

Conversational app builder (alternative to Typeform and Landbot). ([Source Code](https://github.com/baptisteArno/typebot.io))

Powerful group chat application. ([Source Code](https://github.com/zulip/zulip))

Email forwarding service for creating aliases. ([Source Code](https://github.com/anonaddy/anonaddy))

Complete email solution that runs on any webspace with PHP and MariaDB. It supports POP3 catchall mailboxes and can also integrate with Postfix or b1gMailServer if you're running your own server. ([Source Code](https://codeberg.org/b1gMail/b1gMail), [Clients](https://www.b1gmail.eu/en/start/addon-b1gmailserver/))

Your Debian-based data center in a box. A set of general-purpose Ansible roles that can be used to manage Debian or Ubuntu hosts. ([Source Code](https://github.com/debops/debops))

Production-ready fullstack but simple mail server (SMTP, IMAP, LDAP, Antispam, Antivirus, etc.) running inside a container. Only configuration files, no SQL database. ([Source Code](https://github.com/docker-mailserver/docker-mailserver))

SMTP server that sends and receives emails according to a simple configuration file, with an optional web interface that you can use to browse your emails. ([Source Code](https://dovel.email/server/tree.html))

Lets you have an infinite number of unique inboxes. ([Source Code](https://codeberg.org/Inboxen/Inboxen))

Full-featured mail server solution based on Postfix and Dovecot. ([Source Code](https://github.com/iredmail/iRedMail))

All-in-one mail server that implements SMTP (both MTA and MX) and IMAP. Replaces Postfix, Dovecot, OpenDKIM, OpenSPF, OpenDMARC with single daemon. ([Source Code](https://github.com/foxcpp/maddy))

Turns any Ubuntu server into a fully functional mail server with one command. ([Source Code](https://github.com/mail-in-a-box/mailinabox))

Mail server suite based on Dovecot, Postfix and other software, that provides a modern Web UI for administration. ([Source Code](https://github.com/mailcow/mailcow-dockerized))

Simple yet full-featured mail server as a set of Docker images. ([Source Code](https://github.com/Mailu/Mailu))