Instantbird : A multi-protocol instant messaging client

Instantbird is a multi-protocol instant messaging client. Using it, you can connect to all your different IM accounts. It uses the Mozilla rendering engine to display messages, and uses the Pidgin libpurple to connect to the different networks.

• Implementation : C++

GNU SIP Witch : A secure peer-to-peer VoIP server

GNU SIP Witch is a secure peer-to-peer VoIP server. Calls can be made even behind NAT firewalls, and without requiring service providers. SIP Witch can be used on the desktop to create bottom-up secure calling networks and as a free software alternative to Skype. It can also be used as a stand-alone SIP-based office telephone server, or to create secure VoIP networks for an existing IP-PBX such as Asterisk, FreeSWITCH, or Yate.

• Licenses : GPLv3
• Operating Systems : OS Independent
• Implementation : C++

Spicebird : An email and messaging software

Spicebird is an email and messaging software. It provides email, calendaring, and instant messaging and can connect to any standards based server. It is built with an innovative tabbed user interface and high end functionality.

• Licenses : GPL
• Operating Systems : Windows, POSIX, Linux

BitlBee allows users to talk to people on the MSN, ICQ, Jabber, Yahoo!, and AIM networks with any IRC client by emulating an IRC server

BitlBee allows users to talk to people on the MSN, ICQ, Jabber, Yahoo!, and AIM networks with any IRC client by emulating an IRC server. A virtual channel is created with all of the user's buddies in it, who can be talked to in the channel or in a query. Also, one can participate in group chats and chat rooms like they were normal IRC channels.

• Licenses : GPL
• Operating Systems : POSIX, Linux, Solaris, BSD, Windows, Mac OS X
• Implementation : C

Linphone : An audio and video Internet phone with GTK+ and console interfaces

Linphone is an audio and video Internet phone with GTK+ and console interfaces. It uses the SIP protocol, and is compatible with most SIP clients and gateways. It can use various audio and video codecs such as Speex, GSM, G711, ilbc, amr, Theora, H263-1998, MPEG4, H264, and snow.

• Licenses : GPL
• Operating Systems : POSIX, Linux, BSD, FreeBSD, Windows, Mac OS X, iPhoneOS, Android
• Implementation : C

aria2 : A utility for downloading files

aria2 is a utility for downloading files. The supported protocols are HTTP(S), FTP, BitTorrent, and Metalink. It has a powerful segmented downloading ability, downloading a file from multiple sources and multiple protocols and utilizing your download bandwidth to the maximum. It supports downloading a file from HTTP(S)/FTP and BitTorrent at the same time, while the data downloaded from HTTP(S)/FTP is uploaded to the BitTorrent swarm. Using Metalink's chunk checksums, aria2 automatically validates chunks of data while downloading a file like BitTorrent.

• Licenses : GPL
• Operating Systems : POSIX, Linux, Mac OS X, Windows, Cygwin, BSD, FreeBSD
• Implementation : C++

RetroShare : A cross-platform private P2P sharing program

RetroShare is a cross-platform private P2P sharing program. It lets you share securely with your friends, using a web-of-trust to authenticate peers and OpenSSL to encrypt all communication. RetroShare provides file sharing, chat, messages, and channels.

• Licenses : LGPL GPL
• Operating Systems : POSIX, Linux, Windows, mac
• Implementation : C++, Qt

libpff : A library and tools to access the Personal Folder File (PFF) and the Offline Folder File (OFF) forma

libpff is a library and tools to access the Personal Folder File (PFF) and the Offline Folder File (OFF) format. PFF is used by Outlook in PAB (Personal Address Book), PST (Personal Storage Table), and OST (Offline Storage Table) files.

• Licenses : LGPL v3
• Operating Systems : Linux, Windows
• Implementation : C++

The GNU Gatekeeper : A free H.323 gatekeeper based on the OpenH323 project

The GNU Gatekeeper is a free H.323 gatekeeper based on the OpenH323 project. You can use it to manage a Voice-over-IP network and let endpoints (e.g., Netmeeting) communicate through symbolic names. It also has an external interface for billing and other applications. It runs on a number of Unix versions (including Linux and Solaris) and Windows.

• Licenses : GPLv2
• Operating Systems : Mac OS X, POSIX, BSD, FreeBSD, Windows, Linux, Solaris
• Implementation : C++

RetroShare : A cross-platform private P2P sharing program

RetroShare is a cross-platform private P2P sharing program. It lets you share securely with your friends, using a web-of-trust to authenticate peers and OpenSSL to encrypt all communication. RetroShare provides file sharing, chat, messages, and channels.

• Licenses : LGPL, GPL
• Operating Systems : POSIX, Linux, Windows, mac
• Implementation : C++, Qt

kommute : Anonymous File Sharing protect your privacy

Kommute is a file sharing client using the anonymous network MUTE.

• Operating Systems : POSIX, Solaris, BSD, OpenBSD, Windows, FreeBSD, Linux, NetBSD
• Implementation : C++

Yet Another Telephony Engine (Yate) : A next-generation telephony engine

Yate is a next-generation telephony engine. While currently focused on Voice over Internet Protocol (VoIP) and PSTN, its power lies in its ability to be easily extended. Voice, video, data, and instant messaging can all be unified under Yate's flexible routing engine, maximizing communications efficiency and minimizing infrastructure costs for businesses. It supports SIP, H.323, IAX, MGCP, Jingle, Jabber, E1, T1, analogic, robbed bit, ISDN PRI, BRI, and SS7.

• Licenses : GPL
• Operating Systems : POSIX, BSD, FreeBSD, Linux, Windows
• Implementation : C++

AFD : A program to automatically distribute files either locally or to remote hosts

AFD is a program to automatically distribute files either locally or to remote hosts. The files are distributed by using FTP or SMTP, and can be sent in parallel and with priority. It provides a GUI to monitor and control the distribution and extensive logging of all activities.

• Licenses : GPL
• Operating Systems : POSIX, AIX, BSD, FreeBSD, HP-UX, IRIX, Linux, SCO, Solaris
• Implementation : C

IndiMail : A mailing solution built upon qmail and other mailing software

IndiMail is a mailing solution built upon qmail and other mailing software. IndiMail also provides management of virtual domains. IndiMail has the ability to distribute the users across multiple hosts. You can have multiple hosts hosting a domain placed anywhere and tied up by IndiMail. IndiMail has multiple queues (called a queue collection). The system IDs and configuration files used by IndiMail are all configurable through a set of environment variables, allowing you to customize IndiMail the way you want. IndiMail does not use hard-coded uid/gid in the executables and hence makes it easy to distribute a binary package. IndiMail has features that any modern email server should have - DKIM, BATV, greylisting, Filtering capability, SPAM/Virus control.

• Licenses : GPLv3
• Operating Systems : POSIX, Linux
• Implementation : C

Mumble : Low-latency, high quality voice chat software primarily intended for use while gaming

Mumble is low-latency, high quality voice chat software primarily intended for use while gaming. It should compile and run the client out of the box on at least Ubuntu 6.06, and quite likely other distributions as well.

• Licenses : BSD Revised GPL
• Operating Systems : Windows, POSIX, Linux
• Implementation : C++

DSPAM : A server-side statistical anti-spam agent for Unix email servers

DSPAM is a server-side statistical anti-spam agent for Unix email servers. It masquerades as the email server's local delivery agent and effectively filters spam using a combination of de-obfuscation techniques, specialized algorithms, and statistical analysis. The result is an administratively maintenance-free, self-learning anti-spam tool. DSPAM has yielded real-world success rates beyond 99.9% accuracy with less than a 0.01% chance of false positives.

• Licenses : GPL
• Operating Systems : Unix
• Implementation : C

Mumble : Low-latency, high quality voice chat software primarily intended for use while gaming

Mumble is low-latency, high quality voice chat software primarily intended for use while gaming. It should compile and run the client out of the box on at least Ubuntu 6.06, and quite likely other distributions as well.

• Licenses : BSD Revised, GPL
• Operating Systems : Windows, POSIX, Linux
• Implementation : C++

Xplico : An IP traffic decoder that extracts data from an Internet traffic capture

Xplico is an IP traffic decoder that extracts data from an Internet traffic capture. From a pcap file, it can extracts each email (POP, IMAP, and SMTP protocols), all HTTP content, VoIP calls (SIP), and so on. It isn't a packet sniffer or a network protocol analyzer, but rather an IP/Internet traffic decoder or network forensic analysis tool (NFAT).

• Licenses : GPLv2
• Operating Systems : POSIX, Linux
• Implementation : C, SQL, Python, PHP, AJAX

GNU SIP Witch : A pure SIP-based office telephone call server

GNU SIP Witch is a pure SIP-based office telephone call server that supports generic phone system features like call forwarding, hunt groups and call distribution, call coverage and ring groups, holding, and call transfer, as well as offering SIP specific capabilities such as presence and messaging. It supports secure telephone extensions for making calls over the Internet, and intercept/decrypt-free peer-to-peer audio and video extensions. It is not a SIP proxy, a multi-protocol telephone server, or an IP-PBX, and does not try to emulate Asterisk, FreeSWITCH, or Yate.

• Licenses GPLv3
• Operating Systems OS Independent
• Implementation C++

SFLphone : An SIP/IAX2 compatible softphone

SFLphone is an SIP/IAX2 compatible softphone. The goal is to create a robust enterprise-class desktop phone. While it can serve home users very well, it is designed for intensive corporate use.

• Licenses : GPLv3
• Operating Systems : Linux
• Implementation : C++, C, dbus, Glib, GTK 2.0, Qt, XML