Nmap - Nmap Free Security Scanner, Port Scanner, & Network Exploration Tool. Download open source software for Linux, Windows, UNIX, FreeBSD, etc.
ProtonVPN - ProtonVPN is a security focused FREE VPN service, developed by CERN and MIT scientists. Use the web anonymously, unblock websites & encrypt your connection.
Angry IP Scanner - Open-source and cross-platform network scanner designed to be fast and simple to use
OpenVPN - OpenVPN - The Open Source VPN
Advanced IP Scanner - Advanced IP Scanner shows all network devices, gives you access to shared folders, and can even remotely switch computers off. Download it Free.
TunnelBear - Really simple VPN to browse the web privately & anonymously.