Scanopy is for IT teams and MSPs who want a dedicated network diagram automation tool which works alongside their existing monitoring platform. OpenNMS Horizon / Meridian is for larger networks that want protocol-level topology discovery inside a full monitoring platform. Discovery, the four topology views, pricing, and licensing are where the two differ, including OpenNMS Horizon / Meridian's trade-offs.
Scanopy vs OpenNMS Horizon / Meridian: head to head
| Scanopy | OpenNMS Horizon / Meridian | |
|---|---|---|
| DiscoveryProtocols used to find devices and map connections | SNMP LLDP CDP ARP TCP/UDP | SNMP CDP LLDP ICMP [52] |
| ServicesNo No service awareness Basic Common port detection Yes Application-level fingerprinting | Yes250+ types | Basic |
| Network ViewsWhich topology views the tool produces from discovery. L2 Physical switch ports and links L3 Subnets, VLANs, routing Workload VM/container host nesting Application Service-dependency / app grouping Yes supported Tag ? unverified Greyed not supported | ||
| Live UpdatesWhether diagrams update automatically after the initial scan | Yes | Yes |
| Open SourceOSI OSI-approved open source license Source available Source code available, restricted license No Proprietary | OSI AGPL-3.0 | OSI AGPL-3.0 |
| PricingStarting price or pricing model | Starts at $11.99 monthly, unlimited hosts | Free (Horizon); Meridian subscription [55] |
| Also IncludesCapabilities beyond network diagramming | Docker Visualization | Monitoring |
How they compare
OpenNMS is the closest tool on this list to Scanopy on discovery. Its Enhanced Linkd (Enlinkd) daemon runs five link-discovery methods by default: Bridge, CDP, IS-IS, LLDP, and OSPF, and it draws a CDP or LLDP edge only where both devices report each other. That is real protocol-level topology discovery, not a hand-placed diagram, and it covers routing topology as well as Layer 2. Scanopy discovers over the same family of protocols and adds ARP and MAC forwarding tables.
The difference is scope on both sides. OpenNMS is a full network management platform: alerting, performance collection, provisioning, and event correlation, with topology as one view inside it. Scanopy does documentation only, and covers two things OpenNMS does not: per-host service detection across hundreds of service types, and workload and application views showing VMs and containers nested in their hosts and services grouped by the application they make up. It also gets the map out, as exports (image, self-contained HTML, wiki markup, CSV), an embedded live map in a wiki or intranet, or a read-only link that stays current.
Both are AGPL-3.0 and self-hostable, so licence is not the deciding factor. Choose OpenNMS if you want topology inside a platform that also monitors, and you have the capacity to run it. Choose Scanopy if you want documentation that stands on its own, covers workloads and applications alongside L2 and L3, and can be handed to someone as a map. Scanopy runs alongside a monitoring platform rather than replacing one, so running both is a coherent setup.
When to choose which
Choose Scanopy when: Choose Scanopy for a dedicated, living network-documentation tool: automatic L2, L3, workload, and application views, per-host service detection, flat pricing regardless of host count, and a free, self-hostable Community edition. It sits alongside your monitoring stack rather than replacing it.
Choose OpenNMS Horizon / Meridian when: Networks large enough to justify a full NMS, where the team wants alerting, performance collection, and protocol-derived topology from a single platform and has the capacity to operate it.
This is a focused, two-tool comparison. Weighing other options too? See the best OpenNMS Horizon / Meridian alternatives. For all 13 tools side by side, see the full network documentation tools comparison.
Sources
Started as a homelabber, now deep in SNMP MIBs, Layer 3 topology, and service fingerprinting - building the network documentation tool I wished existed.