Web application scanners
Nikto (web application scanner)
Nikto is an open source security scanner which tests web servers for potential vulnerabilities.
Spaghetti (web vulnerability scanner)
Spaghetti is a web vulnerability scanner to find flaws in common web applications and frameworks. It can perform fingerprinting and vulnerability discovery.
Wapiti (vulnerability scanner for web applications)
Wapiti is a security tool to perform vulnerability scans on web applications. It uses fuzzing to detect known and unknown paths, among other tests.
WhatWeb (website fingerprinter)
WhatWeb is a security tool written in Ruby to fingerprint web applications. It helps with detecting what software is used for a particular web application.