MOA is the most popular open source framework for data stream mining, with a very active growing community (blog).

An example of Explainable Machine Learning can be found here.

WEKA (Waikato Environment for Knowledge Analysis) is an open source machine learning software in JAVA. It contains tools for data preparation, classification, regression, clustering, association rules mining, and visualization.

A Python package for online/streaming machine learning.

The Advanced Data mining And Machine learning System (ADAMS) is a flexible workflow engine aimed at quickly building and maintaining data-driven, reactive workflows, easily integrated into business processes, released under GPLv3.