Psi is a free instant messaging application designed for the XMPP network (including Google Talk). Fast and lightweight, Psi is fully open-source and compatible with Windows, Linux, and Mac OS X.
License: Open Source
Psi is designed for lightweight data processing and real-time analytics, making it suitable for smaller datasets and quick deployments. In contrast, Spark is a robust framework that excels in handling large-scale data processing with rich machine learning capabilities.