@ -147,62 +147,56 @@ Some [Groupware](#groupware) solutions also feature calendar/address book editin
* [AgenDAV](http://agendav.org/) - Multilanguage CalDAV web client with a rich AJAX interface and shared calendars support. [Source Code](https://github.com/adobo/agendav) `GPLv3``PHP`
* [CalendarServer](http://trac.calendarserver.org/) - A standards-compliant server implementing the CalDAV and CardDAV protocols. `Apache``Python`
* [calypso](http://keithp.com/calypso/) - A python-based CalDAV/CardDAV server
* [DAViCal](http://www.davical.org/) - A server for calendar sharing (CalDAV)
* [Radicale](http://radicale.org/) - A Simple Calendar and Contact Server
* [calypso](http://keithp.com/calypso/) - A python-based CalDAV/CardDAV server.
* [DAViCal](http://www.davical.org/) - A server for calendar sharing (CalDAV).
* [Radicale](http://radicale.org/) - A Simple Calendar and Contact Server.
* [sabre/dav](http://sabre.io/) - A open source CardDAV, CalDAV and WebDAV server.
* [ownCloud calendar](https://doc.owncloud.org/server/7.0/user_manual/pim/calendar.html) - The ownCloud Calendar app enables you to create and edit events, synchronize to other calendars you might use, and create new, personalized calendars. ([Source Code](https://github.com/owncloud/calendar)) `AGPLv3``PHP`
## Communication systems
### Email
#### Webmail clients
* [Cypht](http://cypht.org/index.html) - A feed reader for your email accounts - `GPL`
* [Mailpile](https://www.mailpile.is/) - Webmail client with search, filtering, encryption features and more ([Source Code](https://github.com/mailpile/Mailpile)) `AGPLv3``Python`
* [RainLoop](http://www.rainloop.net/) - Simple, modern & fast webmail with IMAP/SMTP Support and multi accounting. ([Demo](http://demo.rainloop.net/), [Source Code](https://github.com/RainLoop/rainloop-webmail)). `AGPLv3``PHP`
* [Roundcube](https://roundcube.net) - Browser-based IMAP client with an application-like user interface. ([Screenshots](https://roundcube.net/screens/)) ([Source Code](https://github.com/roundcube/roundcubemail/)) `GPLv3``PHP`
* [SquirrelMail](http://squirrelmail.org) - Another browser-based IMAP client.
* [Exim](http://www.exim.org/) - Message transfer agent (MTA) developed at the University of Cambridge.
* [Haraka](http://haraka.github.io/) - A high-performance, pluginable SMTP server written in JavaScript.
* [MailCatcher](http://mailcatcher.me/) - Ruby gem that deploys a simply SMTP MTA gateway that accepts all mail and displays in web interface. Useful for debugging or development.
* [Maildrop](https://github.com/m242/maildrop) - Disposable email SMTP server, also useful for development.
* [OpenSMTPD](https://opensmtpd.org/) - Secure SMTP server implementation from the OpenBSD project.
* [Postfix](http://www.postfix.org/) - Fast, easy to administer, and secure Sendmail replacement.
* [Sendmail](http://www.sendmail.com/sm/open_source/) - Message transfer agent (MTA).
### Custom
#### Mail Delivery Agents
* [Freenet](https://freenetproject.org/index.html) - Anonymously share files, browse and publish "freesites" (web sites accessible only through Freenet) and chat on forums. ([Source Code](https://github.com/freenet/fred)) `GPLv2``Java`
* [Friends](http://moose-team.github.io/friends/) - P2P chat powered by the web. ([Source Code](https://github.com/moose-team/friends)) `MIT``Nodejs`
* [Jitsi Meet](https://jitsi.org/Projects/JitsiMeet) - Jitsi Meet is an OpenSource (MIT) WebRTC JavaScript application that uses Jitsi Videobridge to provide high quality, scalable video conferences. `MIT ``JavaScript`
* [Jitsi Video Bridge](https://jitsi.org/Projects/JitsiVideobridge) - WebRTC compatible Selective Forwarding Unit (SFU) that allows for multiuser video communication. `Apache``Java`
* [Kandan](http://getkandan.com/) – Kandan is an Open Source Alternative to HipChat. - `AGPL`
* [Let's Chat](https://sdelements.github.io/lets-chat/) - A persistent messaging application that runs on Node.js and MongoDB. `MIT``Nodejs`
* [Mattermost](http://www.mattermost.org/) - Open-source, on-prem Slack-alternative. It can be integrated with [Gitlab](https://about.gitlab.com/). ([Source Code](https://github.com/mattermost/platform)) `AGPLv3/Apache 2.0``Go`
* [Mibew](https://mibew.org) - Mibew Messenger is an open-source live support application written in PHP and MySQL. It enables one-on-one chat assistance in real-time directly from your website. ([Demo](https://mibew.org/demo2), [Source Code](https://github.com/Mibew/mibew)) `Apache``PHP/Javascript`
* [Mumble](http://wiki.mumble.info/wiki/Main_Page) - Low-latency, high quality voice/text chat software. `BSD``C++`
* [Mumblecop](https://bitbucket.org/Flandoo/mumblecop) - Stream audio from youtube and soundcloud, simulate dice rolls, or write your own commands with a simple plugin format. `MIT``Ruby`
* [Node-Chat](https://github.com/IgorAntun/node-chat) - A not-so-basic open-source chat with admin features. - `MIT``Nodejs`
* [RetroShare](http://retroshare.org) - Secured and decentralized communication system. Offers decentralized chat, forums, messaging, file transfer. ([Source Code](https://github.com/RetroShare/RetroShare)) `GPLv2``С++`
* [Rocket.Chat](https://rocket.chat/) – Teamchat solution similar to Gitter.im or Slack. - `MIT`
* [Synapse](https://matrix.org/blog/project/synapse/) - A server for [Matrix](https://matrix.org/), an open standard for decentralized persistent communication. ([Source Code](https://github.com/matrix-org/synapse)) `Apache``Python`
* [Vector](https://matrix.org/blog/project/vector/) - A glossy Matrix web client with an emphasis on performance and usability. ([Source Code](https://github.com/vector-im/vector-web)) `Apache``Javascript`
* [Matrix Console Web](https://matrix.org/blog/project/matrix-console-web/) - A web client meant to be a showcase of Matrix capabilities, and reference implementation of the Matrix standard. ([Source Code](https://github.com/matrix-org/matrix-angular-sdk)) `Apache``Javascript`
* [Syndie](https://www.syndie.de) - Syndie is a libre system for operating distributed forums. `Public Domain``Java`
* [TextBelt](https://github.com/typpo/textbelt) - An outgoing SMS API that uses carrier-specific gateways to deliver your text messages for free, and without ads. ` ⚠ ``MIT``JavaScript`
* [Tox](https://tox.chat/) - A distributed, secure messenger with audio and video chat capabilities. `GPLv3``C`
* [Zulip](https://zulip.org) - Zulip is a powerful, open source group chat application. ([Source Code](https://github.com/zulip/zulip))`Apache 2.0/Other` `Python/Django`
_MDAs - IMAP/POP3 software_
* [Cyrus IMAP/POP3](http://cyrusimap.org/) - Intended to be run on sealed servers, where normal users are not permitted to log in.
* [Dovecot](http://www.dovecot.org/) - IMAP and POP3 server written primarily with security in mind.
_simple deployment of a mail server, e.g. for inexperienced or impatient admins._
* [hMailServer](https://www.hmailserver.com) - Open source e-mail server for Microsoft Windows
* [hMailServer](https://www.hmailserver.com) - Open source e-mail server for Microsoft Windows.
* [Mailcow](https://github.com/andryyy/mailcow) - Mail server suite based on Dovecot, Postfix and other open source software, that provides a modern Web UI for administration. `PHP/Shell/Other``GPLv2`
* [Mail-in-a-Box](https://mailinabox.email/) - Turns any Ubuntu server into a fully functional mail server with one command. `Shell/Other``CC0`
* [iRedMail](http://www.iredmail.org/) - Full-featured mail server solution based on Postfix and Dovecot.
* [Citadel](http://www.citadel.org/) - Feature packed, easy, versatile, and powerful mail server, thanks to exclusive "rooms" based architecture.
* [Modoboa](http://modoboa.org/en/) - Modoboa is a mail hosting and management platform including a modern and simplified Web User Interface. `Python``MIT`
#### Mailing lists
#### Mailing Lists
_Mailing lists servers._
@ -210,39 +204,38 @@ _Mailing lists servers._
* [Sympa](https://www.sympa.org/) - A mailing list manager. `Perl``GPL`
### XMPP
_[Extensible Messaging and Presence Protocol](https://en.wikipedia.org/wiki/XMPP) software_
#### Mail Delivery Agents
_MDAs - IMAP/POP3 software_
#### XMPP Servers
* [Cyrus IMAP/POP3](http://cyrusimap.org/) - Intended to be run on sealed servers, where normal users are not permitted to log in.
* [Dovecot](http://www.dovecot.org/) - IMAP and POP3 server written primarily with security in mind.
* [Metronome IM](https://lightwitch.org/metronome) - Fork of Prosody IM. `MIT``Lua`
* [MongooseIM](https://www.erlang-solutions.com/products/mongooseim-massively-scalable-ejabberd-platform) - Fork of ejabberd.
* [Openfire](http://www.igniterealtime.org/projects/openfire/) - Real time collaboration (RTC) server. `Apache``Java`
* [Prosody IM](http://prosody.im/) - Feature-rich and easy to configure XMPP server. `MIT``Lua`
* [Tigase](https://projects.tigase.org/projects/tigase-server) - XMPP server implementation in Java.
#### XMPP Web Clients
#### Mail Transfer Agents
* [Candy](http://candy-chat.github.io/candy/) - Multi user XMPP client written in Javascript.
* [Converse.js](https://conversejs.org/) - A free and open-source XMPP chat client in your browser ([Source](https://github.com/jcbrand/converse.js)) `MPLv2``Javascript`
* [Kaiwa](http://getkaiwa.com/) - Web based chat client in the style of common paid alternatives. ([Source Code](https://github.com/digicoop/kaiwa))
* [Kontalk](http://kontalk.org/) – Kontalk is an Open Source Messenger, similiar to WhatsApp (app for android only currently), including end-to-end encryption, server is based on Tigase XMPP Server - ([Source Code](https://github.com/kontalk)) `GPLv3`
* [Lets-Chat](http://sdelements.github.io/lets-chat/) - A self hosted chat suite written in Node.
* [Salut à Toi](http://www.salut-a-toi.org/) - Multipurpose, multi frontend, libre and decentralised communication tool. ([Source Code](http://repos.goffi.org/sat)) `AGPLv3``Python`
* [Libervia](http://wiki.goffi.org/wiki/Libervia/en) - Web frontend from Salut à Toi ([Source Code](http://repos.goffi.org/libervia)) `AGPLv3``Python`
* [Exim](http://www.exim.org/) - Message transfer agent (MTA) developed at the University of Cambridge.
* [Haraka](http://haraka.github.io/) - A high-performance, pluginable SMTP server written in JavaScript.
* [MailCatcher](http://mailcatcher.me/) - Ruby gem that deploys a simply SMTP MTA gateway that accepts all mail and displays in web interface. Useful for debugging or development.
* [Maildrop](https://github.com/m242/maildrop) - Disposable email SMTP server, also useful for development.
* [OpenSMTPD](https://opensmtpd.org/) - Secure SMTP server implementation from the OpenBSD project.
* [Postfix](http://www.postfix.org/) - Fast, easy to administer, and secure Sendmail replacement.
* [Cypht](http://cypht.org/index.html) - A feed reader for your email accounts. `GPL`
* [Mailpile](https://www.mailpile.is/) - Webmail client with search, filtering, encryption features and more. ([Source Code](https://github.com/mailpile/Mailpile)) `AGPLv3``Python`
* [RainLoop](http://www.rainloop.net/) - Simple, modern & fast webmail with IMAP/SMTP Support and multi accounting. ([Demo](http://demo.rainloop.net/), [Source Code](https://github.com/RainLoop/rainloop-webmail)). `AGPLv3``PHP`
* [Roundcube](https://roundcube.net) - Browser-based IMAP client with an application-like user interface. ([Screenshots](https://roundcube.net/screens/)) ([Source Code](https://github.com/roundcube/roundcubemail/)) `GPLv3``PHP`
* [SquirrelMail](http://squirrelmail.org) - Another browser-based IMAP client.
* [Freenet](https://freenetproject.org/index.html) - Anonymously share files, browse and publish "freesites" (web sites accessible only through Freenet) and chat on forums ([Source Code](https://github.com/freenet/fred)) `GPLv2``Java`
* [Friends](http://moose-team.github.io/friends/) - P2P chat powered by the web. ([Source Code](https://github.com/moose-team/friends)) `MIT``Nodejs`
* [Jitsi Meet](https://jitsi.org/Projects/JitsiMeet) - Jitsi Meet is an OpenSource (MIT) WebRTC JavaScript application that uses Jitsi Videobridge to provide high quality, scalable video conferences. `MIT ``JavaScript`
* [Jitsi Video Bridge](https://jitsi.org/Projects/JitsiVideobridge) - WebRTC compatible Selective Forwarding Unit (SFU) that allows for multiuser video communication. `Apache``Java`
* [Kandan](http://getkandan.com/) – Kandan is an Open Source Alternative to HipChat. - `AGPL`
* [Let's Chat](https://sdelements.github.io/lets-chat/) - A persistent messaging application that runs on Node.js and MongoDB. `MIT``Nodejs`
* [Mattermost](http://www.mattermost.org/) - Open-source, on-prem Slack-alternative. It can be integrated with [Gitlab](https://about.gitlab.com/). ([Source Code](https://github.com/mattermost/platform)) `AGPLv3/Apache 2.0``Go`
* [Mibew](https://mibew.org) - Mibew Messenger is an open-source live support application written in PHP and MySQL. It enables one-on-one chat assistance in real-time directly from your website. ([Demo](https://mibew.org/demo2), [Source Code](https://github.com/Mibew/mibew)) `Apache``PHP/Javascript`
* [Mumble](http://wiki.mumble.info/wiki/Main_Page) - Low-latency, high quality voice/text chat software `BSD``C++`
* [Mumblecop](https://bitbucket.org/Flandoo/mumblecop) - Stream audio from youtube and soundcloud, simulate dice rolls, or write your own commands with a simple plugin format. `MIT``Ruby`
* [Node-Chat](https://github.com/IgorAntun/node-chat) - A not-so-basic open-source chat with admin features. - `MIT``Nodejs`
* [RetroShare](http://retroshare.org) - Secured and decentralized communication system. Offers decentralized chat, forums, messaging, file transfer. ([Source Code](https://github.com/RetroShare/RetroShare)) `GPLv2``С++`
* [Rocket.Chat](https://rocket.chat/) – Teamchat solution similar to Gitter.im or Slack - `MIT`
* [Synapse](https://matrix.org/blog/project/synapse/) - A server for [Matrix](https://matrix.org/), an open standard for decentralized persistent communication ([Source Code](https://github.com/matrix-org/synapse)) `Apache``Python`
* [Vector](https://matrix.org/blog/project/vector/) - A glossy Matrix web client with an emphasis on performance and usability ([Source Code](https://github.com/vector-im/vector-web)) `Apache``Javascript`
* [Matrix Console Web](https://matrix.org/blog/project/matrix-console-web/) - A web client meant to be a showcase of Matrix capabilities, and reference implementation of the Matrix standard ([Source Code](https://github.com/matrix-org/matrix-angular-sdk)) `Apache``Javascript`
* [Syndie](https://www.syndie.de) - Syndie is a libre system for operating distributed forums. `Public Domain``Java`
* [TextBelt](https://github.com/typpo/textbelt) - An outgoing SMS API that uses carrier-specific gateways to deliver your text messages for free, and without ads. ` ⚠ ``MIT``JavaScript`
* [Tox](https://tox.chat/) - A distributed, secure messenger with audio and video chat capabilities. `GPLv3``C`
* [Zulip](https://zulip.org) - Zulip is a powerful, open source group chat application. ([Source Code](https://github.com/zulip/zulip))`Apache 2.0/Other` `Python/Django`
### Social Networks and Forums
* [Anahita](https://www.getanahita.com/) - Open Source Social Networking Framework & Platform. ([Source Code](https://github.com/anahitasocial) `GPLv3``PHP`
* [Bootcamp](http://trybootcamp.vitorfs.com) - An enterprise social network - [Source Code](https://github.com/vitorfs/bootcamp)
* [Bootcamp](http://trybootcamp.vitorfs.com) - An enterprise social network. - [Source Code](https://github.com/vitorfs/bootcamp)
* [Buddycloud](http://buddycloud.com/) - Tools, libraries, services and a community to build user-to-user, group and social messaging into your app. Saves time. Scales up. Supports you. ([Source Code](https://github.com/buddycloud)) `Apache 2.0``Java/Javascript`
* [BuddyPress](https://buddypress.org/about/) - A powerful plugin that takes your WordPress.org powered site beyond the blog with social-network features like user profiles, activity streams, user groups, and more.
* [Discourse](http://www.discourse.org/) - Advanced forum / community solution based on Ruby and JS - `GPLv2`
* [Elgg](https://elgg.org/) - A powerful open source social networking engine - `GPLv2`
* [Discourse](http://www.discourse.org/) - Advanced forum / community solution based on Ruby and JS. - `GPLv2`
* [Elgg](https://elgg.org/) - A powerful open source social networking engine. - `GPLv2`
* [Flarum](http://flarum.org) - Delightfully simple forums. Flarum is the next-generation forum software that makes online discussion fun again. ([Source Code](https://github.com/flarum/flarum)) `MIT``PHP`
* [FluxBB](http://fluxbb.org/) - Fast, light, user-friendly forum software for your website. ([Source Code](https://github.com/fluxbb/fluxbb)) `GPLv2``PHP`
* [Friendica](http://friendica.com/) - Social Communication Server ([Source Code](https://github.com/friendica/friendica)) `AGPLv3`
* [Gnu Social](https://gnu.io/social/) - Social communication software for both public and private communications
* [Hubzilla](https://github.com/redmatrix/hubzilla) - Independent general-purpose websites that not only connect with their associated members and viewers, but also connect together `MIT``PHP`
* [HumHub](https://www.humhub.org/) - A flexible kit for private social networks ([Source Code](https://github.com/humhub/humhub)) `AGPLv3``PHP`
* [Isso](http://posativ.org/isso/) - A lightweight commenting server written in Python and JavaScript. It aims to be a drop-in replacement for Disqus ([Source Code](https://github.com/posativ/isso)) `MIT``Python`
* [Friendica](http://friendica.com/) - Social Communication Server. ([Source Code](https://github.com/friendica/friendica)) `AGPLv3`
* [Gnu Social](https://gnu.io/social/) - Social communication software for both public and private communications.
* [Hubzilla](https://github.com/redmatrix/hubzilla) - Independent general-purpose websites that not only connect with their associated members and viewers, but also connect together. `MIT``PHP`
* [HumHub](https://www.humhub.org/) - A flexible kit for private social networks. ([Source Code](https://github.com/humhub/humhub)) `AGPLv3``PHP`
* [Isso](http://posativ.org/isso/) - A lightweight commenting server written in Python and JavaScript. It aims to be a drop-in replacement for Disqus. ([Source Code](https://github.com/posativ/isso)) `MIT``Python`
* [Jappix](https://jappix.com/) - Jappix is an open social platform, that let's you easily get or keep in touch with everyone.
* [Loomio](https://www.loomio.org/) - Loomio is a collaborative decision-making tool that makes it easy for anyone to participate in decisions which affect them. ([Source Code](https://github.com/loomio/loomio)) `AGPLv3``Ruby`
* [Movim](https://movim.eu/) - A brand new social network, full of awesome features in a modern and smart interface
* [Movim](https://movim.eu/) - A brand new social network, full of awesome features in a modern and smart interface.
* [Newebe](http://newebe.org/) - A Distributed Social Network. ([Source Code](https://github.com/gelnior/newebe)) `AGPLv3``Python`
* [NodeBB](https://nodebb.org/) - Node.js based forum software built for the modern web. ([Source Code](https://github.com/NodeBB/NodeBB)) `GPLv3``Nodejs`
* [Oxwall](http://www.oxwall.org/) Oxwall is used for a wide range of projects starting from family sites and custom social networks to collaboration tools and enterprise community solutions. ([Source Code](https://bitbucket.org/oxwall/public) `CPALv1``PHP`
* [phpBB](https://www.phpbb.com/) - Flat-forum bulletin board software solution that can be used to stay in touch with a group of people or can power your entire website. `GPLv2``PHP`
* [PPnet](https://github.com/pixelpark/ppnet) Create and host your own social network. `MIT``JavaScript`
* [Pump.io](http://pump.io/) - Stream server that does most of what people really want from a social network ([Source Code](https://github.com/e14n/pump.io))
* [Pump.io](http://pump.io/) - Stream server that does most of what people really want from a social network. ([Source Code](https://github.com/e14n/pump.io))
* [Reddit](https://www.reddit.com/) - Social networking and news website where registered community members can submit content. ([Demo](https://www.reddit.com/) [Source Code](https://github.com/reddit/reddit)) `CPALv1``Python`
* [RedMatrix](http://www.redmatrix.me/) - Complete decentralised publishing, sharing, and communications system ([Source Code](https://github.com/redmatrix/redmatrix))
* [Metronome IM](https://lightwitch.org/metronome) - Fork of Prosody IM. `MIT``Lua`
* [MongooseIM](https://www.erlang-solutions.com/products/mongooseim-massively-scalable-ejabberd-platform) - Fork of ejabberd.
* [Openfire](http://www.igniterealtime.org/projects/openfire/) - Real time collaboration (RTC) server. `Apache``Java`
* [Prosody IM](http://prosody.im/) - Feature-rich and easy to configure XMPP server. `MIT``Lua`
* [Tigase](https://projects.tigase.org/projects/tigase-server) - XMPP server implementation in Java.
#### XMPP Web Clients
* [Candy](http://candy-chat.github.io/candy/) - Multi user XMPP client written in Javascript.
* [Converse.js](https://conversejs.org/) - A free and open-source XMPP chat client in your browser. ([Source](https://github.com/jcbrand/converse.js)) `MPLv2``Javascript`
* [Kaiwa](http://getkaiwa.com/) - Web based chat client in the style of common paid alternatives. ([Source Code](https://github.com/digicoop/kaiwa))
* [Kontalk](http://kontalk.org/) – Kontalk is an Open Source Messenger, similiar to WhatsApp (app for android only currently), including end-to-end encryption, server is based on Tigase XMPP Server. - ([Source Code](https://github.com/kontalk)) `GPLv3`
* [Lets-Chat](http://sdelements.github.io/lets-chat/) - A self hosted chat suite written in Node.
* [Salut à Toi](http://www.salut-a-toi.org/) - Multipurpose, multi frontend, libre and decentralised communication tool. ([Source Code](http://repos.goffi.org/sat)) `AGPLv3``Python`
* [Libervia](http://wiki.goffi.org/wiki/Libervia/en) - Web frontend from Salut à Toi. ([Source Code](http://repos.goffi.org/libervia)) `AGPLv3``Python`