Alertmanager vs Grafana OnCall
A side-by-side comparison of two self-hosted monitoring & status options — licensing, setup difficulty, resource needs, and what each one replaces.
| Feature | Alertmanager | Grafana OnCall |
|---|---|---|
| Deploy effort | Under-an-hour setup | Under-an-hour setup |
| Health score | 92 · Excellent | 15 · At risk |
| Status | Actively maintained | Archived |
| Category | Monitoring & Status | Monitoring & Status |
| License | Apache-2.0 | AGPL-3.0 |
| Language | Go | Python |
| Setup difficulty | Medium | Medium |
| Min. RAM | 64 MB | 512 MB |
| Deployment | docker, kubernetes, binary | docker, kubernetes, helm |
| GitHub stars | ★ 8,627 | ★ 3,886 |
| First released | 2015 | 2021 |
| Replaces | PagerDuty, Opsgenie | PagerDuty, Opsgenie |
What are Alertmanager and Grafana OnCall?
Alertmanager
Alertmanager handles alerts sent by Prometheus and other clients, taking care of deduplication, grouping, and routing to receivers such as email, Slack, or PagerDuty. It also supports silences and inhibition rules.
- Alert deduplication and grouping
- Flexible routing trees
- Silences and inhibition
- Many notification integrations
Grafana OnCall
Grafana OnCall is an on-call management tool that handles alert escalation, schedules, and notifications across phone, SMS, Slack, and more. It deduplicates and routes alerts so the right person is paged.
- On-call schedules and rotations
- Escalation chains
- Phone, SMS, and chat alerts
- Alert grouping and routing
Alertmanager vs Grafana OnCall: key differences
The biggest difference is maintenance: Grafana OnCall's repository is archived and no longer developed, while Alertmanager is actively maintained. Alertmanager is written in Go, while Grafana OnCall is built with Python. Licensing differs — Apache-2.0 for Alertmanager versus AGPL-3.0 for Grafana OnCall. Alertmanager is the lighter option, starting around 64 MB of RAM against 512 MB for Grafana OnCall. Alertmanager is the more established project (first released 2015), while Grafana OnCall arrived in 2021. Alertmanager has the considerably larger community, at 8,627 GitHub stars versus 3,886.
Why pick each one
Choose Alertmanager if…
- Powerful routing logic
- Standard in the Prometheus stack
Watch out for
- YAML config can get complex
- Tied to Prometheus ecosystem
Choose Grafana OnCall if…
- Strong PagerDuty alternative
- Integrates with Grafana
Watch out for
- Several components to deploy
- Telephony needs external provider
Frequently asked questions
Is Alertmanager or Grafana OnCall better?
Neither is universally better. Alertmanager has the larger community; both share a medium setup difficulty, so the decision comes down to features and licensing.
Are Alertmanager and Grafana OnCall free and open-source?
Yes. Alertmanager is licensed under Apache-2.0 and Grafana OnCall under AGPL-3.0. Both can be self-hosted at no software cost.
Can I run Alertmanager and Grafana OnCall with Docker?
Alertmanager: yes. Grafana OnCall: yes.
Which is lighter on resources, Alertmanager or Grafana OnCall?
Alertmanager has the smaller minimum footprint at 64 MB of RAM, compared to about 512 MB for Grafana OnCall. Real-world usage depends on library size, user count, and enabled features.