Building an HTTP Proxy JWT Decoder Extension

Security analysts and developers often need to inspect security tokens on the fly to understand authentication flows and identify vulnerabilities. This text-based course guides you through building a practical HTTP proxy extension designed specifically to extract and decode JSON Web Tokens from request headers. You will start with the core concepts of proxy architecture and token-based authentication before writing clean, functional extension code. By completing this course, you will understand how to interface with proxy APIs, parse HTTP headers, and display decoded payload data in real-time. What you'll learn: - Understand the foundational mechanics of HTTP proxies and extension APIs - Parse JSON Web Tokens to extract headers, payloads, and signature structures - Read and manipulate HTTP request headers programmatically - Build a custom user interface tab within a proxy tool to display decoded data - Apply robust error handling to manage malformed or unsigned tokens - Implement modern coding practices for secure and performant extension development This course begins with essential definitions of proxy extensions and JWT structures, then guides you through step-by-step code implementation, and concludes with testing your extension against live HTTP traffic. Every concept is explained through clear written commentary and structured code examples. This course is designed for beginner security tool developers, ethical hackers, and web application developers looking to customize their security analysis workflows. No prior extension development experience is required, though a basic understanding of HTTP and JavaScript or Java is helpful. Start building your custom security tools today through clear, step-by-step written instruction.