The open-source (GPLv2) VPN protocol that powers most modern VPNs. WireGuard is not a service — it’s a fast, minimal, audited protocol you run yourself with no device or bandwidth limits. Free to self-host on any platform (Linux kernel, Windows, macOS, iOS, Android). No managed free tier; you bring your own server (or pair it with a provider like Tailscale, Mullvad, or Proton VPN).