Explore the intricacies of WebAssembly (WASM) filters and singletons in this 31-minute conference talk by Emmanuel Mayssat. Dive into the development of a custom authentication and authorization system using WASM, covering the decision-making process and development environments on Kubernetes and Docker Compose. Learn about software architecture concepts, including singleton stacks and chained WASM filters, as well as practical aspects such as WASM bytecode download, policy management, and Prometheus metrics integration. Gain insights into library integration, data sharing techniques, hidden headers, code testing strategies, and debugging methods for real-world projects. Explore the considerations for choosing programming languages like C++, Rust, AssemblyScript, and TinyGo, and understand the learning curves, build pipelines, and development velocity using tools like Carvel/YTT.