Alertmanager vs PagerDuty: Which for Alerting?
Alertmanager routes, groups, and silences alerts from Prometheus; PagerDuty is a managed incident-response platform with on-call scheduling and escalation.
Alertmanager handles deduplication, grouping, silencing, and routing of Prometheus alerts to receivers, but it is not a full on-call platform. PagerDuty adds on-call schedules, escalation policies, incident workflows, analytics, and integrations across hundreds of tools as a paid SaaS. They are complementary: Alertmanager wins on open-source alert routing; PagerDuty wins on end-to-end incident response and on-call management.
| Alertmanager | PagerDuty | |
|---|---|---|
| Type | Open-source router | Managed SaaS |
| On-call | No (route only) | Schedules + escalation |
| Incident mgmt | Minimal | Full workflows |
| Cost | Free (self-host) | Per-seat paid |
| Best for | Prometheus routing | On-call + incidents |
Use case and scope
Alertmanager suits teams wanting free, self-hosted alert routing tightly bound to Prometheus. PagerDuty suits organizations needing on-call rotations, escalation, incident workflows, and analytics. A common pattern routes Alertmanager alerts into PagerDuty for the human-response layer.
Ops and CI fit
Alertmanager is a small self-hosted binary you operate; PagerDuty is fully managed. Alertmanager config and routing rules are commonly validated in CI, where faster managed runners speed config tests and rule linting.
Decide with your own numbers, not a feature table
Feature comparisons age badly and rarely decide anything, because both tools in a mature category can do the job. What differs is how each behaves on your repository, and that takes one afternoon to measure.
# time a cold install with each candidate, cache cleared
hyperfine --prepare "rm -rf node_modules" --warmup 1 \
"<tool-a> install" "<tool-b> install"
# and the thing CI actually pays for: a cold run with no local cache
docker run --rm -v "$(pwd):/w" -w /w node:22 sh -c "<tool> install"What actually changes when you switch
- Lockfile format. A switch is a one-way door for anyone still on the old tool until everyone migrates, so plan it as a single coordinated change.
- Resolution strictness. Tools differ on whether an undeclared transitive import works, and the stricter one will surface latent bugs as new failures.
- CI cache configuration. The cache path and key differ per tool; carrying over the old ones silently disables caching.
- Everyone on the team and every runner must move together. Pin the version so they cannot drift.
The verdict
Want free, self-hosted alert routing for Prometheus: Alertmanager. Want full on-call scheduling, escalation, and incident response: PagerDuty. They pair well, with Alertmanager routing into PagerDuty.