#10 of 20 infrastructure monitoring tools · Updated October 2026
OpenNMS review 2026
OpenNMS Horizon and Meridian · Open-source network NOC platform
OpenNMS ranks #10 of 20 infrastructure monitoring tools in the Infrastructure Monitoring Ledger 2026, with a Ledger Index of 65.2 out of 100. OpenNMS offers deep free network, event and scale capability and delivered every 2023-2026 promise, but release pace slowed and it needs specialist skills.
Scores
Source: Infrastructure Monitoring Ledger 2026, edition 2026-10-04. How each score works: methodology.
Pros
- Data collection and scale4.5/5
- Network monitoring4/5
- Alerting and event management4/5
- Security and compliance4/5
Cons
No domain scores 2.5 or lower out of 5. Check the lock-in and buying notes below.
What the Ledger says
OpenNMS is extending a network-first platform with distributed collection, flow processing and ML alarm correlation toward streaming telemetry, new hypervisors and AI agents over MCP. The record shows strong network, event and scale depth and every 2023-2026 promise delivered, but release pace slowed in 2024-2025. Buyers get deep free capability with Horizon, while specialist skills and a small parent company are the main trade-offs.
AI say-do: 2 tracked, 2 delivered GA (ALEC 2.0, DGX templates), 0 dropped; MCP moved from preview to GA as promised. AI is unsupervised alarm correlation and anomaly detection.
Capability by area
Buying, lock-in and release record
Buying and licence (commercial risk)(lower is better)
- Price and licence volatility1.5
- Meridian repackaged into Foundation, Advanced and Enterprise node bands in 2023; AGPLv3 unchanged
- Purchase constraints2
- Horizon free; Meridian subscription only, quote based, enterprise entry price
- Channel and access2
- Open downloads and docs; Meridian repositories behind subscription; no partner programme described
- Owner stability3
- Owned since 2020 by NantHealth, a healthcare software company; subsidiary results not reported separately
- Cost of staying supported1.5
- Horizon updates free; Meridian keeps 3-year support windows
Technical lock-in(lower is better)
- Formats2
- XML config files and PostgreSQL; metrics in Cassandra, ScyllaDB, TimescaleDB or RRD
- Export path2
- Config through ReST API; flows in OpenSearch; no import tools to other products
- Stack coupling2
- Java/Karaf core, PostgreSQL required; standard SNMP, flows, gNMI, OpenTelemetry; own Minion
- Hardware / cloud coupling0
- Any hardware, fully offline
- Skills and tooling coupling3
- OpenNMS XML, requisitions and Karaf skills are specialist and scarce
Release credibility
- Cadence3.5
- Two or three Horizon majors a year to 2022, then 18 months between Horizon 33 (2024-02) and 34 (2025-08)
- Roadmap transparency4
- Public GitHub, docs and issue tracker; direction through blog posts and developer conferences
- Say-do4.5
- 7 of 7 items since 2023 shipped in the named release, no lag recorded
- Velocity3.5
- Several capabilities per major release, slower in 2024-2025
- Lifecycle stability4
- Meridian LTS with 3-year support and backported fixes; Java runtime moves handled in-release
Partners and services
- Partner programme openness2
- No partner programme described in the research
- Multi-tenancy and self-service3
- Minion locations and surveillance categories used by MSPs; no tenant portal or billing
- API and infrastructure-as-code3
- ReST v1 and v2; community Ansible roles; official Helm charts from Horizon 35; no Terraform
- Skills and certification2
- No training or certification described in the research
Alternatives to OpenNMS
Is OpenNMS right for you?
Describe what you run and the free advisor ranks OpenNMS against the other infrastructure monitoring tools for your case.
Questions about OpenNMS
Is OpenNMS any good?
OpenNMS ranks #10 of 20 infrastructure monitoring tools in the Infrastructure Monitoring Ledger 2026, with a Ledger Index of 65.2 out of 100. Its strongest areas are data collection and scale, network monitoring, alerting and event management.
What are the best alternatives to OpenNMS?
The closest by Ledger Index are Nagios XI (64.6), Icinga (64.2), IBM SevOne / Netcool (66.6), SolarWinds (68.3).
How is OpenNMS licensed and sold?
Meridian repackaged into Foundation, Advanced and Enterprise node bands in 2023; AGPLv3 unchanged.
How much lock-in does OpenNMS bring?
OpenNMS scores 9 out of 25 on technical lock-in (lower is better). Export path: Config through ReST API; flows in OpenSearch; no import tools to other products.
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