Online Port scanner AlternativesIP Scanners & Network Monitors like Online Port scanner

Open-source utility for security auditing and network exploration, utilizing raw IP packets to scan hosts and services, identify OS and service versions, and assess network infrastructure, compatible across major operating systems with advanced GUI and tool suite.

Open-source, cross-platform network scanner for fast and simple IP and port scanning. It's lightweight, requires no installation, utilizes multithreading for speed, and is extendable via plugins. It pings IPs, resolves hostnames, determines MAC addresses, provides NetBIOS info, and saves results in various formats.

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.

Reliable and free network scanner to analyse LAN. The program shows all network devices, gives you access to shared folders, provides remote control of computers (via RDP and Radmin), and can even remotely switch computers off. It is easy to use and runs as a portable edition.

Tenable Network Security provides enterprise-class products for gathering, evaluating, communicating and reporting IT security and compliance information.

This is the fastest Internet port scanner. It can scan the entire Internet in under 6 minutes, transmitting 10 million packets per second.