Proxmox

https://www.proxmox.com/en/

Proxmox VE is a complete open-source platform for enterprise virtualization. With the built-in web interface you can easily manage VMs and containers, software-defined storage and networking, high-availability clustering, and multiple out-of-the-box tools on a single solution.

Further Readings

proxmox-helper is a browser extension I wrote to close promox subscription popup automatically, without need to modify the promox server code or setting.