Psi

Psi is an instant messaging client supporting the XMPP protocol, which makes it compatible with a large number of messaging services, such as GoogleTalk, LJTalk, Nimbuzz and HipChat.

Likewise, it works with many other implementations of these services, which can be deployed at the organization level. What is more, thanks to the implementation of gateways, it also lets you communicate with users of proprietary services, like AIM, ICQ, MSNM and YahooM.

The application has a nice and simple-to-use interface, which adapts itself to your system’s configuration to match the selected look. Moreover, you are free to pick the desired colors, icons and emoticons. Other aspects, such as keyboard shortcuts can be customized as well.

Psi is stable and light. Besides, it runs on multiple platforms as it is Java-based and designed on QT. It supports connecting through a proxy and encrypting all the data transferred. However, it also inherits some of the limitations of the XMPP protocol. For instance, it does not support QoS. Moreover, its text-based communication shows a higher network overhead compared to binary solutions. Likewise, it has intrinsic difficulties in terms of transferring large amounts of binary data, which is fortunately solved by opening gateways to other services.