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OpenNMS

opennms.com

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Spec score 8.3 #10 of 36 in Alert Management Software

What it is

OpenNMS is an open-source platform for monitoring faults, performance, traffic, and alarms across local and distributed networks. Horizon is the free community distribution with the newest features; Meridian is the stable subscription version. Data collection supports SNMP, JSON, WinRM, XML, SQL, JMX, SFTP, FTP, JDBC, HTTP, HTTPS, VMware, WS-Management, and Prometheus. Traffic monitoring handles NetFlow v.5/9, IPFIX, and sFlow, with stated capacity above 300,000 flows per second. Minions extend monitoring to remote devices and services, including locations behind firewalls or NAT through ActiveMQ or Apache Kafka. Integrations include email, Slack, Mattermost, scripts or webhooks, Jira, Remedy, TSRM, Grafana, and a REST API. Grafana views can show alarms, outages, KPIs, NetFlow, and data from multiple instances. The software supports API, Linux, self-hosted, and web deployments. Horizon is free; Meridian plans range from $6,000 a year to $66,000 a year, with larger deployments priced on request.

Spec sheet

Purpose
OpenNMS is an open-source network monitoring platform for fault, performance, traffic monitoring, and alarm generation across local and distributed networks.Read 7 Oct 2026 · opennms.com
Integrations
The FAQ lists email, Slack, Mattermost, custom scripts or webhooks, Jira, Remedy, TSRM, Grafana, and a REST API among integrations.Read 7 Oct 2026 · opennms.com
Security
The company says its security program aligns with ISO 27001/27002, CCPA, and GDPR frameworks, and major Meridian versions receive third-party penetration testing and remediation before release.Read 7 Oct 2026 · opennms.com
Support
Meridian subscriptions include support options and severity-based SLAs; the listed standard coverage is 7 a.m. to 7 p.m. ET Monday through Friday, with 24/7 emergency support as an add-on.Read 7 Oct 2026 · opennms.com
Headquarters
Lewisville, Texas, United StatesRead 28 Sep 2026 · opennms.com
Founded
2000Read 28 Sep 2026 · opennms.com
Company
The OpenNMS Group says it was founded in 2004 and provides services from headquarters near Research Triangle, North Carolina; its site contact address is in Lewisville, Texas.Read 7 Oct 2026 · opennms.com
Collection protocols
Its data collection supports SNMP, JSON, WinRM, XML, SQL, JMX, SFTP, FTP, JDBC, HTTP, HTTPS, VMware, WS-Management, and Prometheus.Read 7 Oct 2026 · opennms.com
Distributed monitoring
Minions monitor devices and services at remote locations that the OpenNMS Core cannot reach, including behind firewalls or NAT when connected through ActiveMQ or Apache Kafka.Read 7 Oct 2026 · opennms.com
Scaling and license limits
OpenNMS states there is no built-in per-instance device or alarm limit, while Meridian subscriptions are limited per instance and each software instance requires a subscription.Read 7 Oct 2026 · opennms.com
Support limits
OpenNMS support plans do not cover Linux, PostgreSQL, Grafana, Cassandra, Kafka, or Elasticsearch as third-party products.Read 7 Oct 2026 · opennms.com
Traffic monitoring
It supports NetFlow v.5/9, IPFIX, and sFlow, with stated capacity of 300,000+ flows per second.Read 7 Oct 2026 · opennms.com
Two distributions
OpenNMS is available as Meridian, an optimized stable subscription version, and Horizon, a free community distribution with the newest features.Read 7 Oct 2026 · opennms.com
Visualization
The OpenNMS Grafana plugin can display alarms, outages, KPIs, NetFlow visualizations, and data aggregated from multiple OpenNMS instances.Read 7 Oct 2026 · opennms.com
Zero-trust
OpenNMS describes zero-trust configurations that use encryption within private networks and strong authentication between authorized parties.Read 7 Oct 2026 · opennms.com

Plans and prices

Horizon Free Free Community distribution · Releases early and often · Features may not all be production-ready Read 7 Oct 2026 · opennms.com
Basic $6,000 a year $6,000 / yr 2 Meridian Cores · Meridian Core Repository Read 7 Oct 2026 · opennms.com
Standard $12,000 a year $12,000 / yr 2 Meridian Cores · Up to 1000 Devices · Meridian Core Repository Read 7 Oct 2026 · opennms.com
Essential $49,000 a year $49,000 / yr Up to 2 Meridian Cores and 10 Minions · Meridian Core and Minion Repository Read 7 Oct 2026 · opennms.com
Premier $66,000 a year $66,000 / yr Up to 4 Meridian Cores and 25 Minions · Meridian Core, Minion, and Sentinel Repository Read 7 Oct 2026 · opennms.com
Premier+ Priced on request Contact us More than 4 Meridian Cores and more than 25 Minions · Core, Minion, and Sentinel Repository plus container images Read 7 Oct 2026 · opennms.com

Every OpenNMS plan and price →

Strong points and limits

Strong points

  • Free Horizon community distribution
  • Broad collection protocol support
  • Remote monitoring through Minions
  • Grafana visualization and multiple integrations
  • No built-in per-instance device limit

Limits

  • Horizon features may not be production-ready
  • Meridian subscriptions are limited per instance
  • Third-party products are outside support coverage
  • 24/7 emergency support costs extra

Who it suits

Network teams monitoring distributed infrastructure, traffic, and alarms across reachable and remote locations. Horizon suits free community use; Meridian suits organizations needing subscription support and defined capacity tiers.

Verdict

OpenNMS covers broad network collection, traffic analysis, distributed monitoring, and alarm visualization. Choose between a free, fast-moving Horizon distribution and paid Meridian subscriptions with support options and instance-based licensing.

Where Specifiction places it

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