Alternatives to Cisco Packet Tracer

Marionnet is mainly for teaching computer networks in university laboratories.

Mininet suits developers, researchers and learners working with Linux-based network prototypes or SDN experiments.

IMUNES suits network practitioners, product teams and teaching labs that need IP network emulation on FreeBSD or Linux.

EVE-NG

EVE-NG suits network, security, and DevOps professionals building emulated labs or training environments.

It suits network engineers, learners, and others working on education, certification practice, proofs of concept, demonstrations, or interoperability testing.

Kathará suits educators and developers building network lessons or demos, as well as teams that need a sandbox for production-network tests or protocol development.

Cloonix suits Linux users building or inspecting emulated network topologies with virtual machines and containers.

The Free tier is described as suited to students and hobbyists, while Pro is aimed at professionals and power users.

NetSim is for people and organizations using guided labs to prepare for Cisco certifications, including individuals, businesses, academic institutions, and government entities.

OMNeT++ suits researchers and educators building network simulations, as well as teams in scientific and industrial settings.

ns-3 suits networking researchers and educators, particularly those prepared to write simulation scripts or modify and extend libraries.

QuNetSim suits students, instructors, and developers learning or prototyping quantum-network protocols.

Tetcos lists universities, defence labs, telecom operators, and research groups as NetSim users.