Cyber is a Model Context Protocol (MCP) server designed to empower LLMs in identifying and addressing security vulnerabilities within backend APIs. By providing specialized tools and resources, Cyber streamlines the process of testing for common security issues such as authentication flaws, injection vulnerabilities, data leaks, and inadequate rate limiting. It includes comprehensive resources like security checklists and testing guides, along with support for various authentication methods, enabling thorough security assessments of secured endpoints.