Network / NMS
OpenNMS
The OpenNMS Group
Enterprise-grade open-source fault + performance + flow platform that scales to tens of thousands of devices; used as a carrier-class FOSS NMS.
- Category
- Network / NMS
- License
- Open source
- Deployment
- Self-hosted
- Cost
- Free
- Free tier
- Yes
- Self-host effort
- Heavy
- Maturity
- Established
- Popularity
- ≈1.2k GitHub stars; enterprise-scale FOSS
The catch
Genuinely powerful but heavy and Java-/XML-config-centric — a steep operational learning curve, and "free Horizon vs supported Meridian" means serious deployments effectively want the paid track.
Monitors
NetworkServersMetricsLogs
Protocols
SNMPNetFlow / sFlow / IPFIXSyslogICMP / ping
Capabilities
AlertingDashboardsAutodiscoveryFlow analysisAPI
Built for
EnterpriseMid-market
The honest take
The FOSS option that actually scales to carrier size — if you can stomach the Java/XML learning curve. Most who run it seriously end up on supported Meridian, which is fair.