GNS3 vs NetSim

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.

NetSim is a browser-based network simulator for learning and practicing network configurations. It runs in the browser using WebAssembly and supports command-line practice for Cisco IOS, Huawei VRP and Aruba AOS-CX. NetSim Labs says it includes more than 35 labs from HCIA to HCIE level. The Free plan costs nothing, billed at $0 forever, and includes 10 basic labs, up to 15 devices per topology, AI Copilot with a bring-your-own-key setup, and local storage only. Pro costs $15 a month and adds 35+ advanced labs, unlimited devices, included AI Copilot, cloud sync across devices and priority support. Enterprise has custom pricing and lists SSO/SAML, an instructor dashboard, LMS integration through LTI, custom lab creation and dedicated support. Topology configurations and lab progress stay local unless cloud sync is enabled. The core engine is licensed under AGPL v3, with commercial licenses offered for organizations needing other terms.