Tailcat: Tailscale Without Tailscale, by Tailscale

Tailcat is an open-source Go package and CLI that lets users run a server-side listener and client communicating over Tailscale’s data plane—WireGuard encryption, NAT traversal, and DERP relay—without any Tailscale control-plane components, accounts, or admin privileges. It generates key pairs, creates a base64-encoded address containing public-key and DERP info, and establishes a userspace TCP connection via WireGuard, with optional lock-down of client keys.