- [Hyphanet](https://hyphanet.org/) - Anonymously share files, browse and publish _freesites_ (web sites accessible only through Hyphanet) and chat on forums. ([Source Code](https://github.com/hyphanet/fred)) `GPL-2.0``Java`
- [Jami](https://jami.net/) - Universal communication platform which preserves the user's privacy and freedoms. ([Source Code](https://git.jami.net/savoirfairelinux?sort=latest_activity_desc&filter=jami)) `GPL-3.0``C++`
- [Live Helper Chat](https://livehelperchat.com/) - Live Support chat for your website. ([Source Code](https://github.com/LiveHelperChat/livehelperchat)) `Apache-2.0``PHP`
- [Mattermost](https://mattermost.com/) - Platform for secure collaboration across the entire software development lifecycle, can be integrated with Gitlab (alternative to Slack). ([Source Code](https://github.com/mattermost/mattermost)) `AGPL-3.0/Apache-2.0``Go/Docker/K8S`
- [Notifo](https://github.com/notifo-io/notifo) - Multichannel notification server with support for Email, Mobile Push, Web Push, SMS, messaging and a javascript plugin. `MIT``C#`
- [Novu](https://novu.co/) - Notification infrastructure for developers. ([Source Code](https://github.com/novuhq/novu/)) `MIT``Docker/Nodejs`
- [Chatwoot](https://www.chatwoot.com) - Customer communication platform (alternative to Intercom and Zendesk). ([Source Code](https://github.com/chatwoot/chatwoot)) `⊘ Proprietary``Ruby/Docker/K8S`
- [Mattermost](https://mattermost.com/) - Platform for secure collaboration across the entire software development lifecycle, can be integrated with Gitlab (alternative to Slack). ([Source Code](https://github.com/mattermost/mattermost)) `⊘ Proprietary``Go/Docker/K8S`
- [PrivMX WebMail](https://privmx.com) - 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. `⊘ Proprietary``PHP`
- [Virola Messenger](https://virola.io/) - 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``C++`
- [WorkAdventure](https://workadventu.re) - Virtual office / virtual conference application presented as a 16-bit RPG video game. ([Demo](https://play.staging.workadventu.re/@/tcm/workadventure/wa-village), [Source Code](https://github.com/workadventure/workadventure)) `AGPL-3.0/Commons-Clause``Docker`