Coccinella is a free and open-source cross-platform instant messaging client with a built-in whiteboard for improved collaboration with other people.
Platforms
- Mac
- Windows
- Linux
- BSD




Spreed is described as 'The worldwide unified web conferencing service offering integrated web and telephone conferencing. It is based on Flash Player. Free service includes 3 attendees and max 1.5h meetings. Single events or monthly service can be purchased' and is a web conferencing tool in the office & productivity category. There are more than 100 alternatives to Spreed for a variety of platforms, including Web-based, Windows, iPhone, Android and Mac apps. The best Spreed alternative is Element. It's not free, so if you're looking for a free alternative, you could try Element or Jitsi Meet. Other great apps like Spreed are Wire, WhatsApp, Jitsi Desktop and Element X.
Coccinella is a free and open-source cross-platform instant messaging client with a built-in whiteboard for improved collaboration with other people.




Messenger for Desktop is a wrapper for the official client messenger.com. Therefore it works like a regular browser which can only navigate to the messenger.com web app. MFD doesn't touch your messages, account or personal data. All that is handled securely by Facebook.

aMSN is a free open source MSN Messenger clone. aMSN attempts to emulate the look and feel of Windows Live Messenger, and supports many of its features.
Offline Messaging Voice Clips Display pictures Custom emoticons Multi-.

QuteCom is a community of enthusiasts and developers, creating free software products related to communication over IP. The flagship product of the QuteCom project is a softphone which allows you to make free PC to PC video and voice calls, and to integrate all your IM contacts...

Small program mainly aimed to provide a simple user interface for making VoIP calls with Asterisk PBX (an open source VoIP PBX).
Tkabber is a Free and Open Source client for the Jabber instant messaging system. Its writen in Tcl/Tk, and works on many platforms (tested on Linux, FreeBSD, NetBSD, Solaris, MacOS X and Windows 98/2000/XP).



ÜberConference is the easiest and best way to make conference calls. Simply choose contacts from your address book and your conference will be created instantly. Participants don't even need to call in, as they will be dialed and/or sent an email invite to join.



Pinger lets you text and talk free with the people you care about most, anywhere on the planet. Tap a picture and you'll see all of your communications—texts, pics, calls, voicemails—all in one place.



Extremely low bandwidth video collaboration software that supports application sharing, desktop sharing, file sharing, and PTZ camera control. Also, this client is free without support for commercial, personal, and government use.



Instant messaging with voice and video options, live group video chat for up to 10 participants, public and private rooms, interest communities, mobile and desktop access, user-created rooms, moderation tools, and options for anonymous participation.



Brosix is a secure communication tool for businesses that need a functional way to organize their internal communication.




Spotbros is an app where you can discover and share all types of content through public chat groups (Spots) or with your friends through private chats.


