Icinga 2 vs OpenNMS Horizon
A side-by-side comparison of two self-hosted monitoring & status options — licensing, setup difficulty, resource needs, and what each one replaces.
| Feature | Icinga 2 | OpenNMS Horizon |
|---|---|---|
| Deploy effort | Under-an-hour setup | Under-an-hour setup |
| Health score | 86 · Excellent | 83 · Excellent |
| Category | Monitoring & Status | Monitoring & Status |
| License | GPL-2.0 | AGPL-3.0 |
| Language | C++ | Java |
| Setup difficulty | Hard | Hard |
| Min. RAM | 512 MB | 4,096 MB |
| Deployment | docker, bare-metal, source | docker, bare-metal |
| GitHub stars | ★ 2,239 | ★ 1,173 |
| First released | 2014 | 2000 |
| Replaces | SolarWinds, PRTG | SolarWinds, PRTG |
What are Icinga 2 and OpenNMS Horizon?
Icinga 2
Icinga 2 is a modern monitoring system that checks the availability of network resources and notifies users of outages. It is Nagios-compatible, scales across clusters, and pairs with Icinga Web for a polished interface.
- Distributed cluster monitoring
- REST API for automation
- Nagios plugin compatibility
- Modern Icinga Web UI
OpenNMS Horizon
OpenNMS Horizon is an enterprise-grade network monitoring and management platform that handles fault, performance, and traffic monitoring at scale. It supports SNMP, flow analysis, and event correlation.
- Fault and performance monitoring
- Flow analysis
- Event correlation
- Scales to large networks
Icinga 2 vs OpenNMS Horizon: key differences
Icinga 2 is written in C++, while OpenNMS Horizon is built with Java. Licensing differs — GPL-2.0 for Icinga 2 versus AGPL-3.0 for OpenNMS Horizon. Icinga 2 is the lighter option, starting around 512 MB of RAM against 4,096 MB for OpenNMS Horizon. OpenNMS Horizon is the more established project (first released 2000), while Icinga 2 arrived in 2014.
Why pick each one
Choose Icinga 2 if…
- Scales to large environments
- Active development and community
Watch out for
- Steep initial setup
- Multiple components to manage
Choose OpenNMS Horizon if…
- Released under the AGPL-3.0 license
- First-class Docker support for quick deployment
- Active community (1.2k GitHub stars)
- Written in Java
Frequently asked questions
Is Icinga 2 or OpenNMS Horizon better?
Neither is universally better. Icinga 2 has the larger community; both share a hard setup difficulty, so the decision comes down to features and licensing.
Are Icinga 2 and OpenNMS Horizon free and open-source?
Yes. Icinga 2 is licensed under GPL-2.0 and OpenNMS Horizon under AGPL-3.0. Both can be self-hosted at no software cost.
Can I run Icinga 2 and OpenNMS Horizon with Docker?
Icinga 2: yes. OpenNMS Horizon: yes.
Which is lighter on resources, Icinga 2 or OpenNMS Horizon?
Icinga 2 has the smaller minimum footprint at 512 MB of RAM, compared to about 4,096 MB for OpenNMS Horizon. Real-world usage depends on library size, user count, and enabled features.