Netdata is a monitoring agent and statistics server.

Using plugins it is able to collect a wide variety of system and
application metrics. Metrics can be checked as they're collected to
trigger alarms, streamed in real-time to other Netdata installations,
stored in an internal metrics database, and archived to an external
time-series database.

Metrics can also be presented visually, with a low-latency web UI.

Each Netdata installation is (by default) autonomous, but all can be
integrated into one large distributed application.

Netdata is lightweight, designed to permanently run on all systems
without disrupting their core function. By default, it needs just 1% CPU
