Blazor WebAssembly vs Blazor Server: Choosing the Right Architecture
Introduction
[Enterprise-focused comparison of hosting models—impact on latency, real-time interactions, compliance, scaling, and cost.]
Core Differences
- WebAssembly: Client executes .NET runtime; larger first load.
- Server: SignalR circuit; thin first load; server resource load per connection.
Comparative Flow Diagram
flowchart LR
subgraph WASM[Blazor WebAssembly]
A[Browser] -->|HTTP GET| B[Static Host]
B -->|.wasm + DLLs| A
A -->|HTTPS| C[APIs]
end
subgraph SERVER[Blazor Server]
A2[Browser] -->|Initial HTTP| D[Server App]
A2 <-->|SignalR| D
D -->|Data| C
end
C[(Azure Data Layer)]
Decision Matrix
| Criterion | WebAssembly | Server |
|---|---|---|
| Initial Load | Larger | Smaller |
| Interaction Latency | Client-side | Round-trip |
| Real-Time | Add SignalR | Native |
| Offline | Limited caching | No |
| Security Code Visibility | Public assemblies | Server protected |
Deployment Patterns
- Hybrid (WASM + API microservices)
- Monolithic Blazor Server (App Service)
- WASM + GraphQL gateway
- Real-Time Collaboration (Server + Redis backplane)
Performance Optimization
WebAssembly
- IL trimming & compression
- Lazy load assemblies
- Cache static assets
Server
- Minimize render cycles
- Use Azure SignalR Service for scale
- Async data access & caching
Security & Identity
- WASM: MSAL + Entra ID; avoid secrets in client.
- Server: OIDC middleware; centralized audit logging.
Observability
- OpenTelemetry traces across API + Server.
- Custom UI interaction events.
Sample OpenTelemetry Snippet
builder.Services.AddOpenTelemetry().WithTracing(b => b
.AddAspNetCoreInstrumentation()
.AddHttpClientInstrumentation()
);
CI/CD Outline (GitHub Actions)
name: build-blazor
on: [push]
jobs:
build:
runs-on: ubuntu-latest
steps:
- uses: actions/checkout@v4
- uses: actions/setup-dotnet@v4
with:
dotnet-version: '9.0.x'
- run: dotnet restore
- run: dotnet build -c Release --no-restore
Troubleshooting
| Issue | Cause | Fix |
|---|---|---|
| Large WASM payload | Untrimmed assemblies | Enable trimming & compression |
| Latency in Server | Excessive re-render | Profile components |
| SignalR disconnects | Idle timeout | Adjust keep-alive settings |
| Auth failures | Token config mismatch | Validate Entra ID app settings |
Best Practices
- Prototype both models early.
- Centralize configuration & secrets.
- Automate performance benchmarks.
Key Takeaways
- Blazor Server excels for secure, line-of-business real-time workflows.
- WASM best for globally distributed, low server overhead scenarios.
- Hybrid patterns unlock targeted optimization.
Additional Resources
Which hosting model fits your workload best?