XSSer vs Responder: Which Open Source AI Agent Runtime Environment tool is Best in 2025?

XSSer, also known as Cross-Site Scripter, is a robust, open-source penetration testing tool designed to detect, exploit, and report Cross-Site Scripting (XSS) vulnerabilities in web applications. Built for security researchers and ethical hackers, it automates the process of identifying XSS flaws, including reflected, persistent, and DOM-based vulnerabilities. XSSer is pre-installed on Kali Linux, a leading penetration testing distribution, and supports multiple platforms like Ubuntu, ArchLinux, and Fedora. With features like payload customization, firewall bypass techniques, and detailed reporting, XSSer is a go-to tool for assessing web application security.

Responder is a robust, open-source tool designed for network penetration testing, specializing in Link-Local Multicast Name Resolution (LLMNR), NetBIOS Name Service (NBT-NS), and Multicast DNS (mDNS) poisoning. Pre-installed on Kali Linux, Responder enables cybersecurity professionals and ethical hackers to intercept network authentication requests, capture NTLM hashes, and perform man-in-the-middle (MITM) attacks by mimicking legitimate servers. Developed by Laurent Gaffié, it targets Windows environments where LLMNR and NBT-NS are enabled by default, making it a powerful tool for credential harvesting and network security assessments.