Observability, monitoring and alerting tools in one directory, from the metrics store to the phone that rings at 3am. Open source and commercial, side by side, with free plans and self-hosting marked.
Understand what a system is doing from its telemetry: metrics, logs, traces, profiles and errors.
Check that services, hosts, networks and scheduled jobs are up and healthy, from inside and outside.
All 151 monitoring toolsGet the right person to the problem: routing, notifications, on-call, incident response and status pages.
All 92 alerting toolsEvery listing checked by hand. Last checked 30 September 2026.
How an alert moves from a monitoring tool to a person, and on to the next person when nobody acknowledges.
Levels, waits, targets and repeats in an escalation policy, with example policies, common mistakes and a checklist.
Weekly, daily, primary and secondary, and follow the sun: the common on-call rotation patterns and when each fits.
How to define severity levels by user impact, what each level should trigger, and how severity connects to paging.
Page on symptoms, not causes: the four golden signals, RED and USE, checks from outside, and what makes an alert worth a page.
Why teams stop trusting their alerts, how to measure the noise, and the fixes: delete, wait, group, inhibit, route by urgency and review.
How heartbeat monitoring catches cron jobs that silently stop, and how to set the period and grace time.
SLIs, SLOs and error budgets, and how multiwindow burn-rate alerts page on real risk to users.
What happens after someone acknowledges: declaring an incident, the roles, communication, and the blameless postmortem.
What MTTD, MTTA, MTTR and MTBF measure, where each clock starts and stops, and how to use them without gaming them.
The questions that separate on-call tools: notification methods, schedules, alert sources, pricing, self-hosting, and a short trial plan.
The books, handbooks and essays that most on-call and observability practice comes from, most of them free to read online. See the reading list.
MTTA, dead man's switch, burn rate, flapping: the vocabulary of monitoring and alerting on one page. Open the glossary.
