Cacti vs Flapjack: What are the differences?
Developers describe Cacti as "Cacti stores all of the necessary information to create graphs and populate them with data in a MySQL database". Cacti is a complete network graphing solution designed to harness the power of RRDTool's data storage and graphing functionality. Cacti provides a fast poller, advanced graph templating, multiple data acquisition methods, and user management features out of the box. On the other hand, Flapjack is detailed as "Monitoring notification routing + event processing system". Flapjack is a flexible monitoring notification routing system that handles: alert routing, alert summarisation, your standard operational tasks.
Cacti and Flapjack belong to "Monitoring Tools" category of the tech stack.
Flapjack is an open source tool with 656 GitHub stars and 91 GitHub forks. Here's a link to Flapjack's open source repository on GitHub.