Nmap - Nmap Free Security Scanner, Port Scanner, & Network Exploration Tool. Download open source software for Linux, Windows, UNIX, FreeBSD, etc.
PuTTY - Popular free terminal application. Mostly used as an SSH client.
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.
MobaXterm - Enhanced terminal for Windows with X11 server, tabbed SSH client, network tools and much more
Angry IP Scanner - Open-source and cross-platform network scanner designed to be fast and simple to use
iTerm2 - A terminal emulator for macOS that does amazing things.