XSSer vs Responder vs PoshC2 vs Wapiti: 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.

PoshC2 is an open-source, proxy-aware command and control (C2) framework designed for penetration testing and red teaming, pre-installed on Kali Linux at /usr/share/poshc2. Primarily written in Python3, it offers a modular architecture that supports PowerShell, C#, C++, and Python3 implants, enabling post-exploitation and lateral movement across Windows, Linux, and macOS systems. Developed by Nettitude Labs, PoshC2 provides highly configurable payloads, extensive logging, and Docker support for cross-platform deployment.

Wapiti, pre-installed in Kali Linux, is an open-source web application vulnerability scanner designed for black-box security testing of web applications. Written in Python, it crawls websites to identify scripts and forms, injecting payloads to detect vulnerabilities such as SQL injection, cross-site scripting (XSS), file disclosure, command execution, XML external entity (XXE) injection, CRLF injection, and server-side request forgery (SSRF). Wapiti leverages a Nikto database to search for dangerous files and supports authentication, proxies, Tor, and customizable scan scopes (e.g., page, folder, domain). Its lightweight 1.54 MB footprint and modular design make it ideal for penetration testers and security auditors.