List of free networking stuff for developerππ½
If you're looking for all programming tools around networking (not just free). Check this page List of networking Programming Tools

Netmaker
Connect your devices securely, wherever they are. Netmaker lets you create the fastest possible distributed mesh VPN. Powered by WireGuard.
Tag: vpn, wireguard, remote, cybersecurity, networking
Manage WireGuard networks
Create mesh VPNs
Create gateways into remote environments
Provide private DNS
Automate ACLs
Connect your infrastructure
Administrate with a UI panel