Cisco CML 2.8 for Free with 5 Node Limit
Cisco Modeling Labs (CML) is a network simulation platform for designing, testing, and troubleshooting network topologies. It's Cisco's emulator.
Since Cisco CML 2.8 (released on November 21, 2024) you can download it for free. There is a 5 node limit. You can download it from the Cisco.com website, look for "Modeling Labs Free Tier".
You'll need to run Cisco CML in a virtual machine (VM). If you have an extra machine, you can run it on a hypervisor such as Proxmox.
This is a great way to test Cisco CML before buying it. Also, with 5 nodes there are still plenty of labs you can build.