...It includes a modern GUI built with .NET and WPF that lets users authenticate, choose VPN servers, and configure features like split tunneling or kill switch, while a background Windows service manages VPN connections using the OpenVPN protocol and handles networking tasks such as firewall and adapter configuration. The app integrates a custom TAP driver and a split tunnel callout driver to help route traffic securely and prevent leaks, and is structured so the GUI and service components work together to deliver a smooth user experience on Windows desktops and laptops. ProtonVPN’s Windows client supports both free and paid users with access to Proton’s global server network, encrypted tunnels, and privacy-first policies that block logging and respect user anonymity.