The best free network simulators, and what 'free' really costs
Almost every network simulator advertises a free tier, and almost every one of them means something different by it. Some are free software that needs expensive inputs. Some are free but locked to one vendor's curriculum. Some are free to a point, then metered.
This page lays out what each option actually costs once you include images, hardware, and the hours before your first working ping — because setup time is the cost that most often decides whether you keep practising.
| What's free | The real cost | |
|---|---|---|
| Packet Tracer | The whole application | Desktop install plus a vendor academy account; scoped to that curriculum |
| GNS3 | The software, fully open source | You source and license the OS images; each node is a VM, so RAM is the limit |
| EVE-NG Community | The Community edition | You host and maintain the server; images still licensed separately |
| Cisco CML | Limited or trial options only | Mainstream tiers are a paid annual licence plus your own hypervisor |
| NetForge-AI Free | 5-device lab, Module 1, in-browser AI tutor | Nothing to install; device and save caps until you upgrade |
Free software is not the same as a free lab
GNS3 is the clearest example. The software genuinely costs nothing and is open source, but it emulates rather than simulates, which means it needs real network operating system images — and those are licensed by vendors, not bundled. Add a machine with enough RAM to run several virtual machines at once and the free tool has a real bill attached.
EVE-NG Community sits in the same category with an extra line item: someone has to own the server. That is fine in a company with infrastructure and a person to run it, and much less fine for an individual learner.
Count the setup time, because it decides whether you practise
The most underrated cost is the gap between deciding to practise and being able to. A lab that takes hours to stand up the first time — and a non-trivial amount of remembering every time after — gets used rarely. A lab that opens in a tab gets used in the gaps between other things, which is when most learning actually happens.
This is why time-to-first-ping is worth treating as a headline number rather than a footnote. Emulators measure it in hours. A browser simulator measures it in minutes.
How to choose without overthinking it
If your course hands you files in a specific vendor's format, use that vendor's tool — the decision is already made for you. If you need real vendor OS behavior for expert-level practice or production validation, accept the setup cost and use GNS3 or EVE-NG. If your goal is to understand networking, optimize for the shortest path to seeing a packet move, and pick something with no install.
NetForge-AI's free plan is built for that last case: a five-device lab, the complete first course module, and the in-browser ARIA tutor, with no payment details and nothing to download. It is genuinely enough to learn addressing, VLANs, and basic routing before you decide whether to go further.
The fastest way to compare simulators is to send one ping. Create a free account, drop two PCs and a switch on the canvas, and watch the ARP + ICMP animation — that's the whole pitch.
Try NetForge-AI freeFAQ
What is the best completely free network simulator?
For learning with zero setup, a browser-based simulator is hard to beat — NetForge-AI's free plan gives a five-device lab, a full course module, and an AI tutor with nothing to install. For maximum realism at no software cost, GNS3 is free and open source, provided you can legitimately obtain OS images and have hardware to run them.
Is there a free simulator that needs no download?
Yes. NetForge-AI runs entirely in the browser — no installer, no hypervisor, no images. That makes it usable on school machines, locked-down work laptops, and Chromebooks where desktop simulators are simply not an option.
Do free simulators cover OSPF, VLANs, and spanning tree?
The serious ones do. NetForge-AI implements VLANs and 802.1Q trunking, STP/RSTP/PVST+, EtherChannel, OSPF, EIGRP, RIP, BGP, VRRP, NAT/PAT, and standard plus extended ACLs, all computed from your configuration rather than scripted.
Will a free tier be enough to learn networking?
For the foundations, yes. Addressing, subnetting, switching, VLANs, and basic routing all fit comfortably inside a small topology. Device caps start to bite when you build multi-area or multi-site designs, which is the point at which a paid plan or a full emulator earns its cost.
NetForge-AI is an independent educational platform, not affiliated with, endorsed by, or sponsored by any vendor named on this page. Product names are used for identification and comparison purposes only. Details about third-party products reflect their publicly documented behavior at the time of writing; pricing and features change, so verify current terms with the vendor before deciding.
More comparisons: A Packet Tracer alternative that runs in your browser · GNS3 vs Packet Tracer vs NetForge-AI · Network simulators that run in the browser — no download · A GNS3 alternative you don't have to install · An EVE-NG alternative with nothing to host · A Cisco Modeling Labs (CML) alternative that runs in the browser · A Boson NetSim alternative that runs anywhere · A network simulator built for classrooms · A network simulator that just works on a Mac