Axibase Time Series Database - ATSD is purpose-built for analyzing and reporting on massive volumes of time-series data collected...
Prometheus - An open-source systems monitoring and alerting toolkit.
OpenTSDB - OpenTSDB is a distributed, scalable Time Series Database (TSDB) written on top of HBase.
Datadog - See metrics from all of your apps, tools & services in one place with Datadog's cloud monitoring as a service solution. Try it for free.
Spotify Heroic - Heroic time series database.
Nagios - Complete monitoring and alerting for servers, switches, applications, and services