Zenmap is the official cross-platform GUI for the Nmap Security Scanner. It is free and runs on Linux, Windows, Mac OS X, etc. Zenmap aims to make Nmap easy for beginners to use while providing advanced features for experienced Nmap users.
Zenmap vs Nmap opinions
sn0int is a semi-automatic OSINT framework and package manager. It was built for IT security professionals and bug hunters to gather intelligence about a given target or about yourself. sn0int is enumerating attack surface by semi-automatically processing public information and...
MASSCAN produces results similar to Nmap , the most famous port scanner. Internally, it operates more like scanrand, unicornscan, and ZMap, using asynchronous transmission. The major difference is that it's faster than these other scanners.
runZero provides asset inventory and network visibility for security and IT teams. You can discover your entire inventory including managed and unmanaged devices, on-premises and cloud assets, IT and OT infrastructure, endpoints at work and at home.
Netdiscover is an active/passive address reconnaissance tool, mainly developed for those wireless networks without dhcp server, when you are wardriving. It can be also used on hub/switched networks.This app doesn't have any features at the moment.
Fingbox is a cloud system to monitor and manage your network, based on Fing Apps, Applications and Tools. It's a secure, cross-platform, comprehensive solution to discover devices, scan services, analyze and customize your networks, from anywhere.
A fully automated, active web application security reconnaissance tool. Key features: High speed: pure C code, highly optimized HTTP handling, minimal CPU footprint - easily achieving 2000 requests per second with responsive targets.Discontinued
Skipfish is no longer maintained. Last version, 2.10 beta, released in December 2012, can be still downloaded from Google Code Archive