# GNS3

GNS3 server

Repository: https://github.com/GNS3/gns3-server
Canonical: https://ross.abutalabs.com/products/gns3
Language: Python
License: GPL-3.0
License Family: copyleft
Topics: network, networking, network-emulator
Last push: 2026-08-31T17:03:29+00:00
Link (homepage): http://www.gns3.com

## Health v2 (maintenance only)
Score: 98/100 (v2, computed 2026-09-02T17:46:02.011165+00:00)
- activity 100, release rhythm 95, longevity 100
- inputs: {"age_days": 4724, "days_push": 2, "days_rel": 34, "gap_med": 18.0, "n_releases_24m": 21}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1022, forks 321 (observed 2026-09-01T02:13:54.887459+00:00)

## What it is
GNS3 is a graphical network simulator that lets users design, build, and emulate complex network topologies using real router, switch, and firewall images. It consists of a PyQt6-based GUI client and a Python server backend that runs the emulated nodes.

## Use cases
- simulate network topologies before deploying them
- practice for networking certifications like CCNA or CCNP
- test router and firewall configurations in a lab
- emulate Cisco, Juniper, and other vendor devices
- capture and analyze packets with Wireshark in a virtual lab
- teach networking concepts in a classroom

## When to choose
- you need to emulate real network device images in a GUI-driven topology
- you want a free, open-source alternative to physical network labs
- you need cross-platform support with a mature, actively maintained tool

## When to avoid
- you only need lightweight container-based network testing without a GUI
- you require commercial support or vendor-certified emulation guarantees
- you want a purely CLI-driven or headless network lab

## Facets
- artifact type: application
- maturity: active
- function: simulation, networking, gui, developer-tools
- domain: networking, developer-tools, education
- platform: cross-platform, windows, python
- tags: network-emulator, network-simulation, topology-design, virtualization, gpl-3.0, linux, macos

## Member repositories
- GNS3/gns3-server (backend) score 98
- GNS3/gns3-gui (frontend) score 97

## Provenance
- Observed fields: from GitHub, fetched 2026-09-01T02:13:54.887459+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T02:20:37.824814+00:00, confidence not recorded.
  - readme: https://github.com/GNS3/gns3-server (fetched 2026-09-01T02:13:54.887459+00:00, sha e0ed1dc3fa15)
  - homepage: http://www.gns3.com (fetched 2026-08-29T10:03:40.008124+00:00, sha de32f1d6054e)
  - registry_pypi: https://pypi.org/pypi/gns3-gui/json (fetched 2026-08-29T10:03:40.017089+00:00, sha 11009ed3a185)
  - registry_pypi: https://pypi.org/pypi/gns3-server/json (fetched 2026-08-29T10:03:40.019077+00:00, sha 11009ed3a185)
- Data as of 2026-08-30T08:39:29.467469+00:00.