Tailcat: An open-source CLI for Tailscale’s WireGuard®, NAT traversal, and DERP

Tailcat is an open-source CLI and Go package that enables bidirectional communication using Tailscale's WireGuard, NAT traversal, and DERP data plane without relying on Tailscale's control plane or accounts. It works like netcat but uses Tailscale’s secure magicsock network, requiring no IP addresses, user accounts, or admin privileges. Tailcat allows easy, fast connections between machines even behind NATs, and is especially useful for ad-hoc tasks like file transfers or port forwarding without modifying system configurations. Developed initially as a personal project, it now serves niche use cases and provides a lightweight alternative built on Tailscale’s core networking technology.