Blazor offers two main hosting models for building interactive .NET web applications, and choosing the wrong one can create performance, scalability, or deployment issues. Interviewers use this question to test whether you can reason about runtime architecture and engineering trade-offs.
Compare Blazor Server and Blazor WebAssembly. In your answer, explain:
Go beyond a surface-level definition. A strong answer should cover the request/connection model, dependency on network connectivity, server resource usage, client download size, access to browser capabilities, and how these factors affect architecture decisions in production.
Blazor Server runs component logic on the server, while Blazor WebAssembly runs .NET code inside the browser via WebAssembly. This single difference drives most trade-offs in latency, scalability, resource usage, and deployment.
Blazor Server keeps a persistent SignalR connection and sends UI diffs between browser and server. Blazor WebAssembly performs rendering and event handling locally in the browser, reducing round trips after the app is loaded.
// Same Razor component syntax in both models
<button @onclick="Increment">Click</button>
Blazor Server consumes server memory and connection capacity per active user session because the server maintains component state. Blazor WebAssembly shifts execution to the client, which usually improves horizontal scalability for large user counts.
Blazor Server typically has faster initial load because the browser downloads less application code. Blazor WebAssembly often has a larger initial payload because the runtime and assemblies must be downloaded before the app becomes interactive.
Blazor Server keeps application logic and sensitive code on the server, which can simplify protection of business rules. Blazor WebAssembly exposes downloaded client code to the browser environment, but it can support richer offline and low-connectivity experiences.
