GNS3

At a glance

• Editor score
  9.4 / 10
• Pricing
  Free plan
• Best for
  Free, broad multivendor network labs
• Free plan
  Yes
• Paid from
  Free
• Real-time emulation
  Yes
• Facts checked
  20 Sep 2026

• Where it wins

  • Combines built-in simulation with actual-device emulation
  • Supports local, remote, cloud, and physical-network connections
  • Includes packet capture, Wireshark integration, and a REST API

• Where it doesn't

  • Practical scale depends on available hardware
  • Complex labs may require multiple deployment components
  • Actual-device emulation depends on compatible device images

Our verdict on GNS3

GNS3 is open-source software for building, configuring, testing, and troubleshooting virtual and real networks. It is designed for network engineers, students, educators, and organizations that need multivendor topologies, certification practice, design validation, interoperability testing, or connections between virtual labs and physical networks. Its hybrid model combines simulation of built-in network devices with real-time emulation using actual device images, giving teams options across different lab requirements.

The published product details show a free, open-source model rather than a paid tier structure. GNS3 provides a graphical client alongside local, remote, and cloud server execution, and it can run across Windows, macOS, Linux, local servers, remote servers, and cloud infrastructure. Practical scale depends on available hardware, so larger or more demanding topologies require appropriate compute resources. The deployment model suits teams that want control over where lab workloads run, but it can involve more planning than a single hosted application.

Its strongest differentiator is breadth across lab connectivity and automation. Users can design and visualize network topologies, emulate devices with actual images, support multivendor appliances, connect to physical network interfaces and real networks, capture packets with Wireshark integration, and manage projects, nodes, links, and compute through a REST API. Choose GNS3 if free, flexible, multivendor network labs and hardware-in-the-loop testing matter more than a simplified setup. An alternative may fit better for teams seeking a narrowly focused, fully managed workflow with less responsibility for infrastructure and lab capacity.

Your product? Our editors can test GNS3 in depth and publish a review, labelled as paid · from $149/mo →

GNS3 pricing

GNS3 fact sheet

Alternatives to GNS3

• CMCisco Modeling LabsA Cisco-focused virtual lab with broad automation, integration, and deployment options.9.2
• EVE-NGA broad emulation platform for large, collaborative multivendor network labs.9.0
• NetSim by TetcosA research-focused simulator for detailed wired, wireless, and emulated network studies.8.9

See all GNS3 alternatives →

GNS3 vs the competition

• GCMGNS3 vs Cisco Modeling Labs
• GGNS3 vs EVE-NG
• GGNS3 vs NetSim by Tetcos
• GOGNS3 vs OMNeT++
• GNGNS3 vs ns-3
• GGNS3 vs Containerlab

Compare GNS3 with any tool side by side →

Featured on iTechGuides

GNS3 is listed in our Network Simulation Software directory. Add the badge to your site — it links back to this page.

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Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026

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Last updated 7 Oct 2026 · How we research and update