How to observe your Blazor WebAssembly application with OpenTelemetry and real user monitoring

Observing WebAssembly applications poses unique challenges due to its binary execution in a browser sandbox, which complicates direct introspection compared to traditional web applications. The Bytecode Alliance is working on enhancing WebAssembly's security and observability standards, and Blazor WebAssembly, a framework that compiles C# into WebAssembly, enables developers to use .NET for both client-side and server-side development, providing a streamlined and high-performance development process. The integration of OpenTelemetry with Blazor WebAssembly allows for comprehensive observability by collecting and exporting telemetry data, though the lack of direct HTTP request capabilities in WebAssembly complicates frontend instrumentation. Automated and manual instrumentation using OpenTelemetry in the backend can capture detailed telemetry data, while frontend monitoring can be achieved through real user monitoring capabilities, such as those provided by New Relic. Despite these challenges, the article illustrates a practical approach to gaining insights into Blazor WebAssembly applications by leveraging existing tools and platforms, with the expectation that ongoing community efforts will continue to simplify observability for these applications.