Alertmanager

Alertmanager is the component that sits between Prometheus and the people on call, taking fired alerts and turning them into notifications that are deduplicated, grouped by label, and routed to the right receivers. It handles inhibition so a root cause alert suppresses its symptoms, supports silence windows with expiry, and clusters over gossip so the same alert is not delivered twice.

Teams use it to send low noise paging to one channel and informational alerts to email or chat.

Running it alongside Prometheus on your own hardware keeps alert details inside your network, avoids per-seat tooling fees, and makes routing and silence configuration part of your regular backup.