BPMN.io is a project that provides tools for viewing, annotating, and editing BPMN (Business Process Model and Notation) 2.0 diagrams, as well as CMMN and DMN diagrams, on the web. It's a widely used, open-source toolkit developed and maintained by Camunda. 

yWorks specializes in software solutions for visualizing diagrams and networks, with a focus on creating clear and user-friendly visualizations. Their primary product, yFiles, is a diagramming SDK (Software Development Kit) that allows developers to embed powerful graph and network visualization capabilities into various applications. yWorks also offers other tools like the yEd graph editor and services such as training and consulting.