skipfish is described as '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' and is a vulnerability scanner in the os & utilities category. There are more than 25 alternatives to skipfish for a variety of platforms, including Windows, Linux, Web-based, Mac and SaaS apps. The best skipfish alternative is Nmap, which is both free and Open Source. Other great apps like skipfish are Zenmap, Shodan, NETworkManager by BornToBeRoot and Nessus.