Nmap (Network Mapper)
Website: Nmap
Description: Open-source tool for network discovery and security auditing.
Burp Suite (Community Edition)
Website: Burp Suite Community Edition
Description: Free version of the popular web vulnerability scanner.
SQLmap
Website: SQLmap
Description: Open-source tool for automating the detection and exploitation of SQL injection flaws.
Nikto
Website: Nikto
Description: Open-source web server scanner.
Metasploit Framework
Website: Metasploit Framework
Description: Free, open-source version of the comprehensive penetration testing framework.
OWASP ZAP (Zed Attack Proxy)
Website: OWASP ZAP
Description: Open-source web application security scanner.
John the Ripper
Website: John the Ripper
Description: Open-source password cracker.
Aircrack-ng
Website: Aircrack-ng
Description: Open-source suite for assessing Wi-Fi network security.
Hydra
Website: Hydra
Description: Fast and flexible network login cracker.
Wpscan
Website: Wpscan
Description: Free, open-source WordPress security scanner.