GNS3 (Graphical Network Simulator-3) is an open-source network emulation platform that has become essential for network professionals and certification candidates worldwide.
| Year |
Milestone |
| 2008 |
GNS3 first released by Jeremy Grossmann, Dominik Ziajka, and Piotr Pękala |
| 2010s |
Rapid adoption by network professionals and certification candidates |
| 2015 |
Reached 11 million downloads |
| 2018-2020 |
Transition to QEMU-based emulation, reduced reliance on Dynamips |
| 2022-2024 |
GNS3 VM architecture improvements, enhanced Docker container support |
| 2025 |
Version 3.0.5 released (May 2025) |
| 2026 |
Version 3.0.6 released (January 2026) |
- Jeremy Grossmann - Lead developer and project founder
- Dominik Ziajka - Co-founder
- Piotr Pękala - Co-founder
GNS3 was created to provide a free alternative to expensive commercial network simulators. The initial version relied heavily on Dynamips for Cisco IOS emulation.
- Adopted by major enterprises (Exxon, Walmart, AT&T, NASA)
- Became the de facto standard for CCNA/CCNP/CCIE exam preparation
- Expanded device support beyond Cisco to include Juniper, Arista, and others
- Shift from pure emulation to multi-vendor network simulation
- Integration with virtualization technologies (KVM, VirtualBox, VMware)
- Docker container support for lightweight network services
- Client-server architecture for distributed lab environments
GNS3 is used by:
- Enterprises: Exxon, Walmart, AT&T, NASA
- Educational institutions: Universities and training centers worldwide
- Certification candidates: CCNA, CCNP, CCIE, JNCIA, JNCIP candidates
- Original: Python 2, Qt4, Dynamips
- Modern: Python 3.8+, Qt5/Qt6, QEMU, Docker integration