Skip to content
SPECIFICTION
Get listed

GNS3

gns3.com

Free plan WebWindowsmacOSLinuxSelf-hosted
Visit gns3.com
Spec score 8.0 #8 of 31 in Network Simulation Software

What it is

GNS3 is free, open-source software for emulating, configuring, testing, and troubleshooting virtual and real networks. Its graphical client works with a virtual machine, and servers can run locally or remotely. Users can combine emulated devices running actual images with simulated devices, including a built-in layer 2 switch. It supports appliances from vendors such as Cisco, Brocade, Cumulus Linux, and HPE, as well as Docker, QEMU-based appliances, VMware, VirtualBox, Hyper-V, and connections to real networks. The GNS3 Marketplace offers preconfigured appliance templates with recommended settings. It runs on Windows, macOS, and Linux; documentation recommends the GNS3 VM for most Windows and macOS setups and complex topologies. Users must supply their own Cisco IOS images. There are no monthly or yearly license fees, and device capacity depends in practice on the host computer’s CPU and memory. GNS3 is used for networking education, certification practice, proofs of concept, demonstrations, and interoperability testing. A server has no authentication enabled by default and should be restricted at the network level.

Spec sheet

Purpose
GNS3 lets network engineers emulate, configure, test, and troubleshoot virtual and real networks.Read 29 Sep 2026 · docs.gns3.com
Integrations
GNS3 supports Docker instances, QEMU-based appliances, hypervisors including VMware, VirtualBox and Hyper-V, and connections to real networks.Read 29 Sep 2026 · docs.gns3.com
Security
GNS3 documentation says a GNS3 server has no authentication enabled by default and should be restricted at the network level.Read 29 Sep 2026 · docs.gns3.com
Support
GNS3 points users to its documentation and community for help, questions, and bug reports.Read 29 Sep 2026 · docs.gns3.com
Appliance marketplace
The GNS3 Marketplace provides preconfigured appliance templates that use recommended settings and are tested by GNS3.Read 29 Sep 2026 · docs.gns3.com
Architecture
GNS3 consists of a graphical all-in-one client and a virtual machine, with local or remote server options.Read 29 Sep 2026 · docs.gns3.com
Cisco image requirement
Users must provide their own Cisco IOS images; GNS3 says it cannot provide them.Read 29 Sep 2026 · docs.gns3.com
Emulation and simulation
GNS3 supports both emulated devices running actual images and simulated devices such as its built-in layer 2 switch.Read 29 Sep 2026 · docs.gns3.com
Multi-vendor support
GNS3 supports devices and appliances from multiple network vendors, including Cisco, Brocade, Cumulus Linux, and HPE.Read 29 Sep 2026 · docs.gns3.com
Open source
GNS3 is open source software that users can download and use for free.Read 29 Sep 2026 · docs.gns3.com
Platform requirements
The documentation lists Windows, macOS, and Linux, and recommends the GNS3 VM for most Windows and macOS setups and complex topologies.Read 29 Sep 2026 · docs.gns3.com
Scale limit
GNS3 does not limit the number of supported devices by license; the practical limit is the host computer’s CPU and memory.Read 29 Sep 2026 · docs.gns3.com
Who it is for
GNS3 is used for networking education and certification practice, proof of concepts, demonstrations, and interoperability testing.Read 29 Sep 2026 · docs.gns3.com

Plans and prices

GNS3 Free Open source · no monthly or yearly license fees · device count limited by available CPU and memory Read 29 Sep 2026 · docs.gns3.com

Every GNS3 plan and price →

Strong points and limits

Strong points

  • Open-source software with no license fees.
  • Supports emulated and simulated devices.
  • Works with multiple network vendors and hypervisors.
  • Can connect to real networks.
  • Marketplace provides preconfigured appliance templates.

Limits

  • Cisco IOS images must be provided by users.
  • Device scale depends on host CPU and memory.
  • Server authentication is off by default.

Who it suits

It suits network engineers, learners, and others working on education, certification practice, proofs of concept, demonstrations, or interoperability testing. Users should be prepared to provide Cisco IOS images and manage server access controls.

Verdict

GNS3 offers a broad environment for working with virtual and real networks without a license-based device count. Users need to account for host resources, Cisco image sourcing, and server access security.

Where Specifiction places it

Alternatives to GNS3All alternatives →