shouldiuse.io

VERDICT

Should I use OpenNMS?

OpenNMS is an enterprise-grade network monitoring platform that can be deployed anywhere. Companies in the Fortune 100 use it every day. - opennms.org

Depends. Buy it if you run a large, complex network with dedicated admins and budget for an enterprise support subscription. Small teams with a few dozen devices should pick a lighter free tool instead.

Confidence

Medium. Based on 50+ public sources; user-review sample is thin (9 Capterra reviews), so confidence is medium.

Ratings

  • Value for money
  • Ease of use
  • Feature depth
  • Support qualityNo support evidence in sources
  • Security posture

Pricing

Free, open source

OpenNMS Horizon

ModelNot disclosed
Monthly feesNot disclosed
HardwareNot disclosed
Free tierYes
OpenNMS MeridianNot public; Software Advice lists ~$44,100

Best for

  • Large enterprise networks
  • Teams with dedicated network admins
  • Open-source shops avoiding license fees
  • Distributed multi-site infrastructure

Not for

  • Small teams monitoring a handful of devices — massive overkill
  • Buyers wanting a quick, turnkey cloud setup
  • Organizations without Linux/Java administration skills
  • Anyone unwilling to manage patches and upgrades themselves

Gotchas - check before you buy

high

Meridian subscription pricing is not public; Software Advice lists ~$44,100

medium

Self-hosting means you own patching; CVE-2021-3396 required urgent updates

medium

Two-branch split: fast-moving free Horizon vs. stable paid Meridian — choose deliberately

low

Only 9 Capterra reviews — small feedback sample for a platform this big

Pros and cons

Pros

  • Free, open-source core (Horizon) with no license costs
  • Enterprise-grade scale; claims daily Fortune 100 usage
  • Distributed monitoring via Minion appliance for remote sites
  • Grafana plugin available for dashboarding
  • 4.9/5 average across Capterra and Software Advice reviews

Cons

  • Commercial Meridian pricing listed around $44,100
  • TechRadar hands-on review gave only 3.5/5
  • Multiple CVEs over the years demand prompt patching
  • Very thin review base: just 9 Capterra reviews

Sources & method

Analyzed 9/21/2026 - 10 sources - Actively disclosed security process, but several CVEs require prompt self-patching.

official x2review x4security x2news x2
  • CVE-2021-3396, Security vulnerability disclosed Feb 2021 with urgent update advisory.
  • CVE-2023-0872, Vulnerability in the Horizon REST API listed in NIST NVD.
  • CVE-2016-6555 & CVE-2016-6556, Stored XSS vulnerabilities via SNMP reported by Rapid7.
  • CVE-2026-19182, Authentication bypass vulnerability listed in SentinelOne's database.

Key stats

  • Value for money: 4/5

    Rating

  • Free, open source

    Starting price

  • 10

    Sources

  • Analyzed

  • Value for money: 4/5. Free core; enterprise Meridian subscription is costly
  • Ease of use: 3/5. TechRadar hands-on review scored it 3.5
  • Feature depth: 5/5. Enterprise-scale, distributed Minion monitoring, Grafana integration
  • Support quality. No support evidence in sources
  • Security posture: 3/5. Public security process, but several disclosed CVEs
  • 4.9/5 Capterra rating Only 9 reviews
  • $44,100 Starting price Software Advice listed price
  • Yes Free tier OpenNMS Horizon is free and open source
  • 3.5/5 TechRadar score Hands-on review

Pricing

OpenNMS Horizon

Free, open source

  • Full monitoring platform
  • Community support
  • Faster-changing releases

OpenNMS Meridian

Not public; Software Advice lists ~$44,100

  • Stable long-term release branch
  • Enterprise subscription support
  • Enhanced security capabilities

Security

Actively disclosed security process, but several CVEs require prompt self-patching.

  • CVE-2021-3396Security vulnerability disclosed Feb 2021 with urgent update advisory.⁶
  • CVE-2023-0872Vulnerability in the Horizon REST API listed in NIST NVD.⁷
  • CVE-2016-6555 & CVE-2016-6556Stored XSS vulnerabilities via SNMP reported by Rapid7.
  • CVE-2026-19182Authentication bypass vulnerability listed in SentinelOne's database.

What users say

Ratings are polarized: 4.9/5 on Capterra's small sample versus 3.5/5 in TechRadar's hands-on review, with Reddit discussions questioning its ease of adoption.

Alternatives

Compare OpenNMS with each alternative.

  • Zabbix

    Free open-source monitoring, widely considered easier to deploy

    OpenNMS vs Zabbix

  • PRTG Network Monitor

    Turnkey Windows-based monitoring for small and mid-size teams

  • Nagios

    Classic lighter-weight monitoring; simpler for basic alerting

Full analysis

Based on 50+ public sources; user-review sample is thin (9 Capterra reviews), so confidence is medium.

Powerful free-core network monitoring built for enterprise scale — overkill and complex for small teams.

Methodology

Based on 50+ public sources; user-review sample is thin (9 Capterra reviews), so confidence is medium.

Sources

  1. Enterprise Network Monitoring Platform | OpenNMS Meridianopennms.com
    official
  2. OpenNMS Software Reviews, Demo & Pricing — Software Advicesoftwareadvice.com
    review
  3. OpenNMS Software Pricing — Capterracapterra.com
    review
  4. I tested OpenNMS — TechRadartechradar.com
    review
  5. Does anybody use opennms? — Reddit r/sysadminreddit.com
    review
  6. CVE-2021-3396: OpenNMS Security Vulnerability (Please Update)opennms.com
    security
  7. CVE-2023-0872 Detail — NIST NVDnvd.nist.gov
    security
  8. The OpenNMS Group Releases OpenNMS Meridian 2022businesswire.com
    news
  9. OpenNMS Group Releases Minion Appliancenanthehealth.com
    news
  10. OpenNMS — Wikipediaen.wikipedia.org
    official

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