Kathará vs NetSim

Kathará is a free, open-source system for emulating networks in interactive lessons, demos, production-network sandbox tests, and protocol development. It represents network devices with containers connected through virtual Layer-2 LANs, and scenarios can use Docker or Kubernetes as their virtualization backend. Built-in images include Quagga, FRRouting, Bind, P4, and OpenVSwitch; users can also supply their own container images. A Python package exposes APIs for custom code. Kathará supports Linux, macOS on Intel or Apple Silicon, and Windows 10 and 11. Debian and Ubuntu installations are available through apt, with precompiled packages for other listed distributions. Settings cover IPv6, terminal behavior, volume mounts, and remote Docker or Kubernetes connections. The software depends on Docker by default, and rootless Docker and Podman are unsupported. The project lists version 3.8.3 as covered by security patches. It is free, with a listed price of free.

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.