OWASP Zap is a free, open-source web application security scanner. It helps you automatically find security vulnerabilities in your web applications while you are developing and testing your applications.

Nessus is a proprietary vulnerability scanner developed by Tenable Network Security. It's one of the most popular vulnerability scanners on the market.

OpenSCAP is an open-source tool for automatically verifying the presence of patches, checking system security configuration settings, and examining systems for signs of compromise.

Wireshark is a free and open-source packet analyzer. It is used for network troubleshooting, analysis, software and communications protocol development, and education.

Metasploit is a penetration testing platform that enables you to find, exploit, and validate vulnerabilities.

Fortify offers end-to-end application security solutions with the flexibility of testing on-premises and on-demand to cover the entire software development lifecycle.

Kali Linux is a Debian-based Linux distribution aimed at advanced Penetration Testing and Security Auditing.

Aircrack-ng is a complete suite of tools to assess WiFi network security. It focuses on different areas of WiFi security.

John the Ripper is a free password cracking software tool. It's one of the most popular password testing and breaking programs.

Snort is a free and open-source network intrusion prevention system and network intrusion detection system.

ClamAV is an open-source antivirus engine for detecting trojans, viruses, malware & other malicious threats.

Intruder is a proactive vulnerability scanner that scans you as soon as new vulnerabilities are released.