Best Automated Network Diagram Tool (2026): 13 Compared

· Updated · Maya
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TL;DR: The best automated network diagram tool for most IT teams is one that combines real auto-discovery with exportable, shareable diagrams, not a monitoring dashboard with a map tab bolted on. Most tools marketed as 'automated' fall into two traps: they're monitoring platforms that include mapping as a feature, or manual tools with zero discovery. Here's what each of the 13 tools actually does, what it costs, and which one fits your network.

How to Choose

There are three categories of network diagram tools: monitoring platforms that include mapping as a feature, dedicated diagram tools that focus only on documentation, and manual diagramming tools where you draw everything yourself. The right choice of network diagram software depends on whether you need monitoring bundled in, how often diagrams need to update, and your budget.

Scenario Recommendation
MSP managing client networks Auvik if you want monitoring bundled in (per-device pricing scales with your client base). Scanopy if you want documentation decoupled from monitoring (flat pricing regardless of host count). Head to head: Scanopy vs Auvik.
Documentation independent from monitoring Scanopy gives you a living, interactive map with flat pricing. SolarWinds NTM exports natively to Visio — the right choice if your team standardizes on Microsoft tools. See Scanopy vs SolarWinds NTM.
Large enterprise with automation needs NetBrain. Nothing else on this list operates at the same scale with the same automation integration. See Scanopy vs NetBrain.
Diagrams bundled with monitoring If you already use Auvik, PRTG, Domotz, or ManageEngine for monitoring, use their built-in mapping. No reason to add another tool for something your monitoring platform already does.
One-time diagram for a presentation or project draw.io or Lucidchart. Draw it once, export it, done. draw.io is free. Lucidchart is better for team collaboration.
Budget monitoring + mapping Domotz ($1.50/device/mo) or ManageEngine ($95/yr)
Free and self-hosted LibreNMS for monitoring with basic maps. NetDisco for Layer 2 topology discovery. Scanopy Community Edition for documentation-focused mapping. draw.io for manual diagrams. All free.

What "Automated" Actually Means

"Automated" means the tool discovers your network and produces a diagram without you drawing anything. Most tools on this list do that. draw.io and Lucidchart don't - they're manual diagramming tools included because they show up in every "best network diagram tool" list. (Here's a deeper look at how automated network documentation works.)

SNMP (Simple Network Management Protocol)
The primary protocol used by network diagram tools to query devices for identity, interface, and neighbor data. Most tools on this list require SNMP to be enabled on managed devices.
LLDP (Link Layer Discovery Protocol)
A vendor-neutral protocol that network devices use to advertise their identity and capabilities to directly connected neighbors. Used by diagram tools to map physical Layer 2 topology.
CDP (Cisco Discovery Protocol)
Cisco's proprietary equivalent of LLDP. Many diagram tools support both CDP and LLDP to discover neighbor relationships on mixed-vendor networks.
Layer 2 vs Layer 3 topology
Layer 2 maps show physical switch-to-switch connections and VLAN assignments. Layer 3 maps show IP subnets and routing relationships. Some tools produce both from a single scan.
Service discovery
Identifying what software or services (web servers, databases, DNS) are running on each host, beyond just detecting that the host exists. Nmap and Scanopy perform deep service fingerprinting; most other tools on this list do not.

Why Pricing Models Matter

Most teams need both monitoring and documentation. The question isn't whether to buy a monitoring tool, it's whether your documentation should be priced like one.

Per-device pricing fits monitoring because monitoring's value is per-device, and it can be tuned to match. You watch critical devices closely and can sample, throttle, or skip the rest, so paying in proportion to what you actively monitor lines up with the value you get (and with the cost, since continuous polling, storage, and alerting genuinely scale per device).

Documentation works the opposite way. Its value is in completeness. A diagram that covers 80% of your devices isn't 80% as useful, it's close to useless, because the gaps are exactly where you get burned. You can't sample documentation by criticality the way you can monitoring, so charging per device penalizes the one thing that makes documentation worth having: the complete picture. It also creates a backwards incentive, where documenting more of your network costs you more, when full coverage was the whole point.

That's why Scanopy prices flat regardless of host count. Keeping documentation priced independently also means you can switch monitoring platforms without losing your maps.

Full Comparison

The table breaks each tool down by which views it actually renders: Layer 2 physical (switch-to-switch) topology, Layer 3 logical (IP subnet and routing) mapping, workload (VM and container) nesting, and application dependency maps. Most tools cover one or two of these. Few cover all four.

ToolProduct name and link to vendor siteDiscoveryProtocols used to find devices and map connectionsNetwork 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
EnvironmentsWhere the tool discovers/maps: on-prem and/or public cloud (AWS, Azure, GCP).ServicesNo No service awareness
Basic Common port detection
Yes Application-level fingerprinting
Live UpdatesWhether diagrams update automatically after the initial scanOpen SourceOSI OSI-approved open source license
Source available Source code available, restricted license
No Proprietary
PricingStarting price or pricing modelAlso IncludesCapabilities beyond network diagramming
Dedicated Diagram Tools
ScanopySNMP LLDP CDP ARP TCP/UDP L2L3WorkloadApplicationOn-prem Yes240+ types YesOSI AGPL-3.0Starts at $11.99 monthly, unlimited hosts Docker Visualization
SolarWinds NTMSNMP WMI CDP LLDP ICMP [3]L2L3Workload ?ApplicationOn-prem No YesNo Perpetual ~$1,570 (subscription shift unclear) [44]
NetBrainSNMP CDP LLDP ARP SSH/CLI L2L3WorkloadApplicationOn-prem AWSAzureGCP [21]No YesNo Enterprise (contact sales)
FaddomNetFlow/sFlow [23]L2L3Workload ?ApplicationOn-prem Basicapp dependencies [23]YesNo Free up to 50 servers then from $19,000/yr [24]
Monitoring Platforms with Diagrams
AuvikSNMP CDP LLDP ARP [1]L2L3WorkloadApplication ?On-prem AWSAzureGCP [20]Basic [2]YesNo Per-device (contact sales) Monitoring Traffic Analysis
PRTGSNMP WMI ICMP [13]L2L3Workload ?ApplicationOn-prem No YesNo Free up to 100 sensors then tiered [4]Monitoring Traffic Analysis
DomotzSNMP ARP ICMP CDP LLDP mDNS NetBIOS [5]L2L3 ?Workload ?Application ?On-prem Basic [6]YesNo $1.50/device/mo [7]Monitoring RMM
ManageEngine OpManagerSNMP CDP LLDP ARP [8]L2L3WorkloadApplicationOn-prem No YesNo From $95/yr (10 devices) [9]Monitoring
Discovery Tools
Nmap + ZenmapICMP ARP TCP/UDP L2L3WorkloadApplicationOn-prem Yes NoSource available NPSLFree
LibreNMSSNMP CDP LLDP [10]L2L3WorkloadApplicationOn-prem No NoOSI GPL-3.0Free Monitoring
NetDiscoSNMP CDP LLDP ARP [12]L2L3WorkloadApplicationOn-prem No YesOSI BSDFree
Manual Diagramming
draw.ioNo L2L3WorkloadApplicationNo NoOSI Apache-2.0Free
LucidchartNo L2L3 ?Workload ?Application ? AWSAzureGCP [22]No NoNo From $9/user/mo [11]

Full disclosure: Scanopy is our product. We built this list to be useful whether you pick us or not. Vendor details are sourced from official documentation, published pricing, and community reports as of June 2026. Features, pricing, and capabilities may have changed since publication. Check each vendor's website for the latest information.

Monitoring Platforms with Diagrams

These are monitoring tools first, and strong ones. Network diagrams come included as part of the monitoring package. If you already use one of these for monitoring, the built-in mapping may be all you need. If you use a different monitoring stack, or want documentation that isn't tied to your monitoring vendor, a dedicated tool gives you more flexibility.

Auvik

The strongest option for MSPs who want monitoring and network maps in one platform. Auvik is cloud-managed network monitoring that discovers devices via SNMP, CDP, LLDP, and ARP, then builds real-time topology maps that update continuously.

Best for: MSPs who need monitoring, alerting, and network maps in one cloud-managed platform

Discovery: SNMP, CDP, LLDP, ARP. NetFlow for traffic analysis. Cloud-hosted with an on-site collector agent. Discovers across AWS, Azure, and GCP via cloud APIs alongside on-prem SNMP/LLDP.

Network views: Discovers VMs and containers and shows them as nodes on the L2/L3 map, but no host-to-VM nesting view (VM detail lives in a monitoring dashboard). [37] [39]

Diagrams: Interactive topology maps with real-time updates and Layer 2/3 views. Auto-discovered topology renders at both layers, updates as devices change state, and stays readable in larger environments.

Pricing: Per-device (contact sales). Auvik does not publish pricing. Multiple device categories (network infrastructure, endpoints, servers) charged at different rates — request a quote for current pricing.

Deployment: Cloud-hosted SaaS. One collector deployed per network site forwards data to Auvik's platform. No software on monitored devices.

Where it fits: If you're an MSP that needs monitoring, alerting, config backup, and network maps in one platform, Auvik is a strong option. The topology mapping is a core feature with Layer 2/3 views, device grouping, and real-time link status — not an afterthought.

Trade-off: Documentation is coupled to Auvik's per-device pricing and platform. If you already run a different monitoring stack (LibreNMS, Zabbix, PRTG), adding Auvik for diagrams means paying for monitoring capabilities you already have.

PRTG Network Monitor

Best for teams already running Paessler for monitoring who want built-in mapping. PRTG is a full monitoring stack with auto-discovery and interactive maps — it has been around since 2003 and has a large installed base. PRTG counts sensors, not devices — most users average 10 sensors per device, so a 1,000-sensor license typically covers around 100 devices.

Best for: Teams already invested in the Paessler ecosystem who want built-in topology mapping alongside monitoring

Discovery: SNMP, WMI, ICMP. NetFlow and packet sniffing for traffic analysis. Self-hosted on Windows.

Network views: No native auto L2/L3; automatic L2 maps require the third-party UVexplorer add-on. [32]

Diagrams: 2D and 3D maps generated from discovery data. Functional, not the prettiest.

Pricing: Free up to 100 sensors then tiered. Not 100 devices - a single device can use multiple sensors.

Deployment: Self-hosted on Windows Server 2016+. PRTG Hosted Monitor available as cloud alternative. Core server with optional remote probes for distributed monitoring.

Where it fits: If you already use PRTG for monitoring and want basic topology visibility, the built-in maps avoid adding another tool. The maps show what PRTG discovers, which is thorough.

Trade-off: Mapping is secondary to monitoring. The diagram feature exists to visualize what PRTG monitors, not to produce shareable documentation.

ManageEngine OpManager

Best budget option for mid-market teams that want monitoring and topology maps at a fraction of Auvik's per-device cost. OpManager provides agentless network monitoring with Layer 2/3 auto-discovery and topology maps, plus rack and floor plan views that most monitoring tools lack. Scales up to 30,000 devices with a distributed monitoring architecture.

Best for: Mid-market IT teams that want monitoring and visualization at a lower per-device cost

Discovery: SNMP, CDP, LLDP, ARP. Auto-maps port-level connectivity.

Network views: Host-to-VM and VM-to-datastore virtualization maps. [27] [38]

Diagrams: Topology maps, rack views, floor plan views. More visualization options than most monitoring tools.

Pricing: From $95/yr (10 devices). Professional from $145/year. Free edition available (3 devices).

Deployment: Self-hosted on Windows or Linux. Agentless — central server polls devices via SNMP, WMI, CLI.

Where it fits: Mid-market teams that want monitoring and visualization in one tool at a lower per-device cost than Auvik. The visualization options (rack views, floor plans) are unusually good for a monitoring tool.

Domotz

The most affordable monitoring platform with network maps — best for cost-conscious MSPs. Domotz offers remote monitoring and management with network mapping, popular as a lower-cost Auvik alternative. A single collector deployed to the client's network provides a real-time inventory within minutes. No endpoint agents required.

Best for: Cost-conscious MSPs who need monitoring, remote access, and basic network maps at a transparent price

Discovery: SNMP, ARP, ICMP, CDP, LLDP, mDNS, NetBIOS. Cloud-hosted with an on-site agent.

Network views: L2 map confirmed; L3/VLAN mapping is not documented in Domotz help docs. [29]

Diagrams: Auto-generated topology maps. Functional. The focus is remote access and monitoring, with mapping as a supporting feature.

Pricing: $1.50/device/mo. Free tier covers 1 managed device with unlimited discovery. Published and transparent.

Deployment: Cloud-hosted SaaS. One collector per network — runs on Linux, Raspberry Pi, Docker, or NAS. No endpoint agents.

Where it fits: MSPs who want monitoring, remote access, and basic network mapping at a fair price. Domotz is frequently recommended as a fair-priced option in MSP communities.

Trade-off: Diagrams are secondary to remote access and monitoring. If documentation is your primary goal, the mapping features may not go deep enough.

Dedicated Diagram Tools

These exist specifically to discover and map networks or the applications running on them. Not monitoring platforms. No alerting, no traffic analysis, no config backup. Their entire purpose is producing accurate diagrams.

SolarWinds Network Topology Mapper

Best for organizations that need compliance-ready Visio exports. NTM scans your network and generates topology diagrams exportable to Visio, PDF, and PNG. It is a standalone Windows application, separate from the SolarWinds Observability platform.

Best for: Enterprise teams that standardize on Microsoft tools and need Visio-native network diagram exports

Discovery: SNMP, WMI, CDP, LLDP, ICMP. Scan-on-demand (not continuous). Supports scheduled scans. Also discovers VMware and Hyper-V environments.

Network views: L2 and L3 diagrams from a single scan. [3]

Diagrams: Multiple diagram types from a single scan (Layer 2, Layer 3, physical). Exports to Visio with auto-populated SmartShapes. Auto-layout with manual override.

Pricing: Perpetual ~$1,570 (subscription shift unclear). SolarWinds moved to subscription-only licensing across its product line in 2025. Renewal prices have reportedly increased significantly post-acquisition by Turn/River Capital.

Deployment: Windows desktop application. Requires .NET 3.5 and 4.8. No web interface, no cloud option. Scans from the machine it's installed on.

Where it fits: Enterprise teams that need compliance-ready documentation with Visio exports. The Visio export alone makes it the default choice in organizations that standardize on Microsoft tools.

Trade-offs: Requires Windows (.NET 3.5 and 4.8). No web-based access, no embeddable maps, no API. NTM has received only maintenance updates since roughly 2016, with no new discovery or mapping features. SolarWinds staff confirmed in 2017 that there is no product roadmap. The product still works, but active development has shifted to SolarWinds Observability. The SolarWinds brand also carries baggage from the 2020 supply chain incident, though NTM is a separate, much simpler product.

Scanopy

Full disclosure: Scanopy is our product. We've tried to be honest about every tool on this list, including our own. Scanopy is an automated network documentation tool built for IT teams that need living network maps that work alongside their monitoring platform. It deploys a lightweight daemon that discovers your network and builds an interactive topology map that updates on a schedule. A single scan produces four views you can switch between: L2 physical, L3 logical, workloads, and applications.

Best for: IT teams and MSPs who want a dedicated network diagram automation tool which works alongside their existing monitoring platform

Discovery: SNMP, LLDP, CDP, ARP, TCP/UDP. One daemon per network. No agents on endpoints, no SSH credentials. SNMPv1, v2c, and v3 (AuthPriv) are all supported, with credentials applied network-wide or pinned per host.

Service discovery: This is where Scanopy differs from most tools on this list. Beyond mapping devices and connections, Scanopy fingerprints 240+ service types per host: databases, web servers, DNS, DHCP, Docker containers, print services, and more. Most network mapping tools tell you a device exists at an IP address. Scanopy tells you what it's running. When you click a host on the topology map, you see every detected service, not just the host itself.

Diagrams: One scan produces four interactive views you can switch between: L2 physical (switch ports and links), L3 logical (subnets and routing), workloads (Docker containers and what they run), and applications (services grouped into the apps they belong to). Topology snapshots version your network state over time, so you can see what changed between scans. Shareable via link (no per-seat licensing). Exportable as SVG, PNG, HTML, Confluence, Mermaid, and PDF. Embeddable via iframe.

Pricing: Starts at $11.99 monthly, unlimited hosts. Free self-hosted Community edition available.

Deployment: Cloud-hosted SaaS or self-hosted via Docker. One daemon per network — no agents on endpoints, no inbound firewall rules.

Where it fits: MSPs documenting client networks, IT teams that need documentation independent from their monitoring stack, and anyone who wants network maps without deploying another monitoring platform. Pairs well with whatever monitoring tool you already use.

What Scanopy doesn't do: Monitoring, alerting, traffic analysis, config backup, patch management, software license tracking. It's a documentation tool. If you need monitoring, use a monitoring tool alongside it.

This is a live Scanopy map you can interact with.

NetBrain

The only tool on this list built for large-scale network automation. Enterprise-grade dynamic network mapping with troubleshooting workflows — NetBrain maps sit at the center of a broader automation platform.

Best for: Large enterprises that need network maps integrated with automation and troubleshooting workflows

Discovery: SNMP, CDP, LLDP, ARP, SSH/CLI. Deep integration with network automation workflows. Discovers AWS VPC/EC2, Azure VNet/VM, and GCP VPC/VM with hybrid on-prem/cloud path mapping.

Network views: Virtualization maps (ESXi/vSwitch/VM) and application-path mapping, all on one dynamic map. [34] [35] [36]

Diagrams: Dynamic maps that tie into troubleshooting runbooks and automation playbooks. Maps can trigger actions, not just display data.

Pricing: Enterprise (contact sales). Not published.

Deployment: On-premises server or NetBrain-hosted cloud. Central server polls devices via SNMP and SSH/CLI — no per-device agents.

Where it fits: Large, complex networks where diagrams aren't just documentation but part of the operational workflow. NetBrain handles networks with thousands of devices and integrates maps directly into troubleshooting runbooks and automation playbooks.

Trade-off: Overkill for anything smaller than a large enterprise. The pricing and complexity reflect that. Community experiences are polarized: some teams report excellent results, while others have struggled with map accuracy for years. One r/networking user spent two years and "hundreds of thousands of dollars" before abandoning it and reverting to manual Visio diagrams. A thorough PoC is essential before committing.

Faddom

Agentless application dependency mapping (ADM) for hybrid and multi-cloud infrastructure. Faddom builds real-time maps of how servers, applications, and services depend on each other, aimed at data center migration, cloud transition planning, and change management. Its headline claim is a first map in under 60 minutes, and reviews corroborate the fast time-to-value.

Best for: Enterprise IT teams mapping application dependencies for data center migrations and cloud transitions

Discovery: NetFlow/sFlow. Discovery is agentless and credential-free. Instead of polling devices, Faddom observes network traffic (NetFlow, sFlow, or a packet copy) to infer dependencies automatically. That means no agents to roll out, but it typically requires NetFlow/sFlow configuration or port mirroring, which needs network-team buy-in.

Network views: Application view is automatic, inferred from observed traffic (NetFlow/sFlow); does no network-layer L2/L3 topology. [23]

Service discovery: Faddom maps application dependencies (which services talk to which), not the device-level service fingerprinting that Scanopy or Nmap do. It enriches maps through integrations with Kubernetes and APM tools like Datadog.

Diagrams: Real-time application dependency graphs spanning on-prem, AWS, Azure, and GCP. It does not produce network-layer (Layer 2/3) topology — the focus is app-to-app relationships, not switch-port physical maps.

Pricing: Free up to 50 servers then from $19,000/yr. Pricing is public, which is rare in this category. A free Community tier covers up to 50 servers (described as "limited time access," so permanence is unclear). Paid plans start at $19,000/year for up to 300 servers (SMB tier) and scale to custom enterprise pricing. Modular: you pay for servers, modules, and users.

Deployment: Self-hosted appliance (on-prem or cloud), also available via the AWS, Azure, and GCP marketplaces. No per-host agents, but it needs access to network traffic.

Where it fits: Mid-to-large enterprise IT operations teams planning migrations or cloud moves who need an automatic picture of application dependencies without deploying agents. The public pricing and 50-server free tier make it evaluable without a sales process, which is unusual for ADM.

Trade-offs: ADM-only scope. No network-layer topology, no CMDB, ITAM, or service management (per third-party analysis). Native ITSM integrations are limited to ServiceNow and Splunk. The traffic-capture dependency (NetFlow/sFlow or port mirroring) is a real setup hurdle, and the $19,000/year floor puts it out of reach for SMB and mid-market budgets.

Manual Diagramming

These tools don't discover your network. You draw the diagram yourself. They show up in "automated network diagram" recommendations constantly, so they're worth covering to clarify what they actually do.

draw.io (diagrams.net)

The best free option for one-time, hand-drawn network diagrams. draw.io is an open-source diagramming tool with extensive network shape libraries — the most popular free alternative to Visio.

Best for: Anyone who needs a one-time, hand-crafted network diagram for a presentation or project

Discovery: You place shapes and draw connections manually. You can import from CSV or XML if you build the data pipeline yourself.

Network views: Manual diagramming only, no discovery.

Diagrams: Highly customizable. Huge icon libraries (Cisco, AWS, Azure, generic network). Export to everything. Works offline.

Pricing: Free.

Deployment: Browser-based at diagrams.net or desktop app (Electron — Windows, macOS, Linux). Confluence and Jira plugins available. No network interaction.

Where it fits: One-time diagrams, architecture documentation, presentations. If you need a diagram for a specific project or meeting and you're willing to draw it, draw.io is excellent.

The catch: The diagram is a snapshot of the moment you drew it. It won't update when your network changes. If you're looking for automated, continuously updated diagrams, draw.io isn't that. But for a well-crafted, specific-purpose diagram, nothing beats the flexibility of drawing it yourself.

Lucidchart

Best for teams that need real-time collaboration on professional diagrams. Lucidchart is cloud-based diagramming with multi-user editing and imports infrastructure data from AWS, Azure, and GCP.

Best for: Teams that need polished, collaborative network diagrams for documentation or cloud architecture reviews

Discovery: No on-prem network scanning. Cloud architecture import via Lucidscale — connects to AWS, Azure, and GCP accounts and auto-generates topology diagrams from live infrastructure.

Network views: Auto-views come only from the Lucidscale cloud import (AWS/Azure/GCP), not on-prem topology. [33]

Diagrams: Professional-grade output. Real-time collaboration. Extensive template library. Integrates with Google Workspace, Atlassian, Microsoft.

Pricing: From $9/user/mo. Free tier available (3 editable documents). Team plans from $9/user/month billed annually. See current pricing for latest rates.

Deployment: Cloud-hosted SaaS. Browser-based, no installation. Cloud import available for AWS/Azure/GCP topology via Lucidscale.

Where it fits: Teams that need polished, shareable diagrams for documentation, presentations, or cloud architecture reviews. Lucidchart supports real-time multi-cursor editing, inline commenting, version history, and integrates with Confluence, Jira, Google Workspace, and Microsoft Teams.

The catch: Same as draw.io for on-prem networks: you're drawing the diagram, not discovering it. The cloud import feature is useful for AWS/Azure/GCP environments but doesn't help with physical networks, switches, or on-prem infrastructure.

Discovery Tools

LibreNMS

The best free self-hosted monitoring option, with limited mapping. LibreNMS is open-source network monitoring with auto-discovery. Topology mapping is secondary and manual: the legacy Weathermap plugin is deprecated (it does not run on supported PHP versions), so mapping uses the Custom Maps feature. Requires PHP 8.2+ and MariaDB on Linux. Central server polls devices via SNMP — no per-device agents required.

Best for: Teams with Linux skills that want free, self-hosted monitoring with basic topology visualization

Discovery: SNMP, CDP, LLDP

Network views: L2 map built from xDP (CDP/LLDP) and ARP; no L3 subnet map. [30]

Diagrams: Topology visualization is a secondary feature. The legacy Network Weathermap plugin is deprecated and does not work on supported PHP versions, so LibreNMS points users to its Custom Maps feature, where the layout is placed by hand. New devices are not added to the map automatically.

Pricing: Free.

Deployment: Self-hosted on Linux (Ubuntu, Debian, CentOS). Docker available. Requires MariaDB and PHP 8.2+. Central server polls via SNMP — no per-device agents.

Where it fits: Teams with Linux server management skills that want free monitoring with some topology visualization. If you're already running LibreNMS for monitoring, the weathermap plugin adds basic mapping without another tool.

Trade-off: Topology visualization is a community plugin, not a first-class feature. Setup requires Linux, PHP, and database administration. The monitoring side is strong; the diagramming side is minimal.

NetDisco

The most-recommended open-source network discovery tool in sysadmin and networking communities. NetDisco is a web-based network management tool that discovers devices via SNMP and maps Layer 2 topology using CDP and LLDP neighbor data. Originally developed at the University of California, Santa Cruz, actively maintained since 2003.

Best for: Network teams that want free, open-source Layer 2 topology discovery and device tracking

Discovery: SNMP, CDP, LLDP, ARP. SNMP-based device discovery with CDP/LLDP neighbor detection and ARP/MAC table correlation. Tracks switch port usage, VLAN assignments, and device locations over time.

Network views: Layer 1/2 neighbor map (CDP/LLDP); explicitly no L3 routing or subnet mapping. [31]

Diagrams: Web-based topology maps with device groupings configurable via config file. Maps take some effort to get looking the way you want, but device groupings work well. Not as polished as commercial tools, but functional.

Pricing: Free.

Deployment: Self-hosted on Linux. Requires Perl and PostgreSQL. Docker image available. Self-contained central server polls via SNMP — no per-device agents.

Where it fits: Network teams comfortable with Perl and Linux administration who want a free, battle-tested tool for Layer 2 discovery and device tracking. Strong at answering "what device is on which switch port?" questions.

Trade-off: Perl-based, which limits the contributor pool. Topology visualization is functional but not modern. Requires Linux, PostgreSQL, and some configuration effort. No service detection beyond basic SNMP data. Mapping is a feature of a broader network management tool, not the primary focus.

Nmap + Zenmap

The go-to tool for one-off network scanning and security audits, not ongoing documentation. Nmap is the standard open-source network scanner. Zenmap is its official GUI, which includes basic topology visualization of scan results.

Best for: Security audits, one-off network discovery, and as the discovery layer in custom automation pipelines

Discovery: ICMP, ARP, TCP/UDP. Port scanning, service fingerprinting, OS detection. Nmap's service detection is thorough: it doesn't just find open ports, it identifies what's running on them.

Network views: The Zenmap topology tab is a traceroute hop graph, not an L2 or L3 map. [17]

Diagrams: Zenmap generates a simple topology view from scan results. Functional for visualizing a single scan, but not a full network diagram tool. For more polished output, export Nmap data (XML) to Graphviz, D3.js, or import into draw.io.

Pricing: Free.

Deployment: Runs on Linux, macOS, Windows, FreeBSD. No server component. Scans from wherever you run it — no agents on targets.

Where it fits: Security audits, one-off network discovery, and as the discovery layer in custom automation pipelines. If you want to know what's on your network right now and what services are running, Nmap is the fastest path. Pair it with a rendering tool for diagrams.

Trade-off: No continuous updates, no topology mapping (LLDP/CDP), no persistent documentation. Each scan is a snapshot. Zenmap's visualization is minimal. For ongoing, automated diagrams, Nmap is the discovery step, not the whole solution.

Scanopy Community Edition

The best free self-hosted option for automated network documentation. Scanopy CE is the free, self-hosted edition with the same discovery engine as the paid product — SNMP, LLDP, CDP, ARP — with an interactive topology map and service detection. Open source and runs on your own hardware.

Best for: Teams that want automated network documentation on their own infrastructure with no SaaS dependency

Discovery: SNMP, LLDP, CDP, ARP. One daemon, no per-device agents.

Network views: Same engine and four views as Scanopy SaaS; application view is user-defined. [19]

Diagrams: Interactive topology map with service and interface detail. Exportable as SVG, PNG, HTML, Confluence, Mermaid, and PDF.

Pricing: Free. Free to self-host, capped at one network and one seat. A commercial license lifts those caps for business self-hosting; managed cloud plans are available too.

Deployment: Self-hosted via Docker, Proxmox, or Unraid. One daemon, no external dependencies beyond PostgreSQL. Same discovery engine as Scanopy SaaS.

Where it fits: Teams that want automated network documentation on their own infrastructure with no SaaS dependency. The free Community edition is AGPL-3.0 and limited to a single network and a single seat; teams that need more take a commercial self-host license or move to the managed cloud plans.

Trade-off: Self-hosted, so you manage updates and the host it runs on. The Community edition is AGPL-3.0 and capped at one network and one seat; a commercial license removes those caps for business self-hosting, with managed cloud hosting as a separate option.

Honorable mentions

Graphviz / D3.js. Rendering engines, not discovery tools. If you've already got network data from another source (Nmap scans, SNMP polls, API calls), Graphviz and D3 can turn it into a diagram. This is the DIY path. Extremely flexible, significant engineering effort required.

How We Compiled This

Every capability claim in this comparison (pricing, discovery methods, service detection, and which view types each tool supports) is sourced to the vendor's own documentation, with inline citations you can check. I verified the figures in June 2026. Where a vendor's docs don't actually confirm a capability, I marked it "unclear" rather than guessing. I built Scanopy, so I have a horse in this race, but the goal here is an honest map of the category. Where a competitor is genuinely stronger at something, I say so.

Sources

[1] Auvik - How does Auvik discover network topology and device information?
[2] Auvik - Can Auvik discover services on my network?
[3] SolarWinds - Network Topology Mapper
[4] Paessler - PRTG Pricing
[5] Domotz - Agentless Network Discovery for MSP Client Onboarding
[6] Domotz - Device TCP/UDP Ports/Services Discovery
[7] Domotz - Pricing
[8] ManageEngine - Discover Networks
[9] ManageEngine - OpManager Editions
[10] LibreNMS - Auto-Discovery
[11] Lucidchart - Pricing
[12] NetDisco - Documentation
[13] Paessler - PRTG System Requirements
[14] Domotz - Agentless Network Discovery
[15] ManageEngine - Agentless Monitoring
[16] LibreNMS - Installation Guide
[17] Nmap - Download / Platforms
[18] Scanopy - Documentation
[19] Scanopy - Community Edition
[20] Auvik - Cloud Collector Installation
[21] NetBrain - Discovering and Visualizing Public Cloud
[22] Lucidscale - Automated Cloud Visualization
[23] Faddom - Agentless Application Dependency Mapping
[24] Faddom - Pricing
[25] NetBrain - Discovering and Visualizing Virtualization (ESXi host, vSwitch, VM)
[26] Auvik - How does Auvik discover network topology and device information? (L1/L2/L3, ESXi host-to-VM)
[27] ManageEngine OpManager - Layer 2 Maps
[28] ManageEngine OpManager - VMware Monitoring (host-to-VM, VM-to-datastore maps)
[29] Domotz - Network Topology Mapping (VLAN/subnet, L2/L3)
[30] LibreNMS - Network Map (Layer 2 links via xDP and ARP)
[31] NetDisco - Network Map (layer1/layer2, not L3 routing/subnets)
[32] Paessler - PRTG has no native Layer 2 topology mapping (use UVexplorer)
[33] Lucid - Lucidscale cloud visualization (cloud-only, no on-prem topology)
[34] NetBrain - Dynamic Map (Layer 2 and Layer 3 topology)
[35] NetBrain - Visualize VMware vCenter Networks (ESXi host and VM relationships on dynamic maps)
[36] NetBrain - Mapping Application Dependencies (A/B Path traffic-flow map)
[37] Auvik - Network Topology Mapper (visualizes physical wiring, VLANs, VMs, containers)
[38] ManageEngine OpManager - Virtual Maps (Host-to-VM, Host-to-Datastore)
[39] Auvik - VMware hypervisor dashboard (VMs listed in a dashboard, not a host-to-VM nesting map)
[40] NetBox - Network Source of Truth (DCIM and IPAM)
[41] NetBox - Topology visualization via community plugin (netbox-topology-views)
[42] NetBox Labs - Pricing (Cloud and Enterprise contact sales)
[43] NetBox - Open source (Apache-2.0), GitHub
[44] SolarWinds NTM - Pricing (TrustRadius)

Frequently Asked Questions

What is the difference between a network diagram tool and a network monitoring tool?

A network diagram tool discovers devices and connections, then produces a visual topology map. A monitoring tool tracks device health, bandwidth, and alerts over time. Some monitoring platforms (Auvik, PRTG, Domotz, ManageEngine) include basic mapping as a feature. Dedicated diagram tools (Scanopy, SolarWinds NTM, NetBrain) focus entirely on producing accurate, shareable maps without bundling monitoring.

How often should automated network diagrams be updated?

It depends on how often your network changes. Tools like Scanopy, Auvik, and Domotz update maps continuously or on a schedule (hourly to daily). SolarWinds NTM runs on-demand scans. For most IT teams, daily or weekly updates catch device additions and topology changes. Environments with frequent changes (cloud, DevOps) benefit from continuous updates.

Can network diagram tools discover cloud infrastructure?

Some can. Lucidscale (part of the Lucid suite) imports AWS, Azure, and GCP topology via cloud APIs. NetBrain and Auvik offer cloud API connectors for hybrid on-prem/cloud maps. Most on-prem-focused tools (SolarWinds NTM, PRTG, Domotz, LibreNMS, NetDisco) only discover devices reachable via SNMP, LLDP, or ARP on local networks.

Do I need SNMP enabled for automated network discovery?

For most tools on this list, yes. SNMP provides device identity, interface details, and neighbor relationships via LLDP/CDP. Without SNMP, discovery is limited to IP-level scanning (ping sweeps, ARP). Nmap can identify services via port scanning without SNMP, but topology mapping relies on SNMP neighbor tables for accurate connection data.

What is the most common reason automated network diagrams are inaccurate?

Incomplete SNMP coverage. If SNMP is not enabled on all managed devices, or if community strings are misconfigured, the tool only sees a partial network. Other common causes include firewalls blocking discovery traffic, unmanaged switches that do not respond to SNMP, and stale ARP caches on routers. Running a manual spot-check after initial discovery helps identify gaps.

How do network diagram tools handle VLANs and subnets?

Tools using SNMP and LLDP/CDP can discover VLAN assignments and map devices to subnets automatically. SolarWinds NTM, NetBrain, and NetDisco are particularly strong at Layer 2 topology including VLAN boundaries. Monitoring-focused tools like Auvik and PRTG show VLAN data as part of device detail but may not visualize VLAN segmentation as a distinct diagram layer.

Try Scanopy

Scanopy deploys a lightweight daemon that discovers your network and builds a live topology map. No per-device fees, unlimited hosts. It pairs with whatever monitoring tool you already use.

Maya, Founder

Started as a homelabber, now deep in SNMP MIBs, Layer 3 topology, and service fingerprinting - building the network documentation tool I wished existed.