VictoriaMetrics

Scalable datastore for metrics, events, and real-time analytics

Add-on agent to generate and expose cluster-level metrics.

Agent for collecting, processing, aggregating, and writing metrics, logs, and other arbitrary data.

Highly available Prometheus setup with long term storage capabilities. A CNCF Incubating project.

Nightingale is to monitoring and alerting what Grafana is to visualization.

highlight.io: The open source, full-stack monitoring platform. Error monitoring, session replay, logging, distributed tracing, and more.