Overview

Instead of reproducing network devices in a separate simulation model, Kathará represents them as containers linked by virtual Layer-2 LANs. That makes it useful when a course or development workflow benefits from containerized network components and repeatable scenarios. Teams can use it for teaching, production-network sandbox testing, and protocol development, though the Docker requirement makes it a less natural fit for environments that cannot run Docker.

Docker and Kubernetes are both supported as deployment backends, giving teams a choice between a familiar local container setup and a Kubernetes-backed environment. The project is open source and free, with a Python package for calling its features from custom code. Those qualities suit technical users who want to build Kathará into their own workflows rather than treat it as a standalone network simulator.

Key features

Container-based network scenarios

Virtual Layer-2 LANs connect containerized devices, allowing scenarios to use network software rather than only abstract device models. Built-in images include Quagga, FRRouting, Bind, P4, and OpenVSwitch, and teams can bring their own container images. That breadth is useful for lessons and protocol work that need specific software, while requiring users to be comfortable working with containers and assembling the scenario they need.

Backend and automation choices

Scenarios can run through Docker or Kubernetes. The Python APIs provide a route to programmatic control from custom code, which can help teams incorporate emulation into development or teaching workflows. Configuration also covers IPv6, terminal behavior, volume-mount policy, remote Docker connections, and Kubernetes API parameters, giving operators control over several practical aspects of a deployment.

Security and operations

The project asks users to report suspected vulnerabilities by issue or email and says it will respond within 48 hours. Its policy says patches are released only for the last version and identifies version 3.8.3 as supported. Teams with stricter maintenance requirements should account for that limited patch coverage when deciding whether Kathará belongs in a production-adjacent workflow.

Docker is the default operational dependency; rootless Docker and Podman are unsupported. That restriction can rule out environments built around rootless containers or Podman. Bug reports go to the GitHub repository, while security-related reports are directed to the Kathará mailing list.

Pricing

Free open-source software: 0.00 USD per free. The free plan provides Kathará without stated usage limits or seat caps, and there are no paid plans. That makes it accessible for courses, individual developers, and teams evaluating network emulation without a software subscription. The main cost to weigh is operational: users still need a compatible Docker or Kubernetes setup, and Docker remains the default requirement.

Platforms

Kathará supports Linux, macOS, and Windows 10 and 11, as well as self-hosted deployments and an API. Linux installation packages are available through apt for Debian and Ubuntu, with precompiled packages for other listed distributions. macOS downloads support both Intel and Apple Silicon. This range makes it possible to use the tool across common desktop systems, though the Docker dependency still shapes what those installations can do.

Who it's for

Kathará is best suited to educators building interactive network lessons, developers working on protocols, and infrastructure teams that want a container-based sandbox for network scenarios. Python APIs and support for custom images make it especially appealing when emulation needs to be driven by code or tailored to a particular software stack. It is a weaker choice for users who cannot operate Docker, need rootless Docker or Podman, or require broader security-patch coverage.

Pros and cons

Pro: Containerized devices and virtual Layer-2 LANs. Scenarios can use real network software components rather than relying only on abstract models.
Pro: Docker and Kubernetes backends. Teams can choose between the default Docker approach and a Kubernetes-backed deployment.
Pro: Built-in and custom images. Quagga, FRRouting, Bind, P4, and OpenVSwitch provide ready-made options, with custom container images available for other needs.
Pro: Python APIs and no-cost access. Custom code can call Kathará features, and the open-source plan is free without stated usage limits.
Con: Docker is central to operation. Rootless Docker and Podman are unsupported, limiting fit for teams that standardize on either.
Con: Patch support is narrow. Security patches apply only to the last version, so teams need to account for version currency.

Alternatives

Browse Network Simulation Software for a broader comparison. Mininet is another free option across Linux, macOS, Windows, and self-hosted/API environments; choose it when its permissive BSD license fits, while accounting for its Linux kernel requirement and one-server CPU and bandwidth limits. Containerlab is also free and spans Linux, macOS, Windows, web, and self-hosted/API environments; it may suit teams seeking that alternative, provided they can use a Linux server or VM, Docker, and sudo for some operations.

OMNEST offers a paid commercial annual license with quotation-based pricing and a free trial, making it an option for readers who prefer a commercial license. EVE-NG has a freemium plan capped at 7 nodes per instance and 63 nodes per lab, so it may suit users whose labs fit those limits. IMUNES is another free option for readers comparing open-source network emulators.

NetSim by Tetcos offers a free Lite plan for individual use and an academic plan with 100 nodes and 35+ built-in lab experiments; it is worth considering for individual or academic use. OMNeT++ offers a free academic public license for noncommercial teaching and research, with a separate license required for commercial use. Cloonix is free AGPLv3 software for Linux hosts, making it an alternative for teams committed to a Linux host.

Verdict

Choose Kathará if you need free, container-based network emulation for teaching, protocol development, or sandbox testing—and value Docker or Kubernetes backends, custom images, and Python automation. Look elsewhere if rootless Docker or Podman is required, or if the last-version-only security patch policy does not meet your operational needs.

	Cisco Packet Tracer	Kathará
Free plan	Yes	Yes
Free trial	No	No
Paid from	Free	Free
Open source	No	No
Platforms	Linux, macOS, Windows	api, Linux, macOS, self-hosted, Windows
Free plan	Yes	Yes
Deployment options	desktop	desktop
Automation API	Yes	Yes
Simulation model	—	emulation

Cisco Packet Tracer vs Kathará

Cisco Packet Tracer

Kathará