Blazor Server vs. WebAssembly: Choosing the Right Path for Your Project

So, you’ve been looking into creating a new web app with Blazor but have run into one dilemma: do you go with Blazor WebAssembly (WASM) or Blazor Server for your application and components?

Blazor Server

Blazor Server fully runs the application on the backend. The C# and Razor code is run on the backend and generates client side HTML and Javascript on the frontend. User interaction on the frontend is sent to and from the server. The server processes the action, updates the app’s UI, and sends the changes back to the user’s browser. Blazor Server uses a SignalR connection (a WebSocket connection) to maintain real-time communication between the server and the frontend client. 

This means that the browser doesn’t execute any application logic and most of the work is done on the server. This is beneficial for a few reasons:

• Lightweight on the client side: The browser won’t need to download the entire app to run

• Smaller initial load time: No large app or runtime download, leading to faster initial load times.

• Centralized Application Logic:All logic resides on the server, simplifying updates and maintenance.

Now, there are some downsides to using Blazor Server, including:

• Constant Server Connection: This won’t work well in environments where connection may drop unexpectedly

• Latency-sensitive: Actions can feel sluggish if the server is far or the connection is slow

• Lower Scalability: The server maintains persistent connections with all clients, which can strain resources as the number of users increases.
  
  
• Higher Resource Demand: Each connection consumes server resources, making it less scalable for large applications without careful optimization.

Blazor WebAssembly 

Blazor WebAssembly (WASM) is Blazor’s other hosting model. The entire app is downloaded to the user’s browser and is run locally. WASM executes C# code in the browsers runtime. It doesn’t require constant communication with the server unless doing things like fetching data.

Some of the pros of using WASM:

• Rich Client-Side Experience: Faster interactions mean the actions don’t depend on a server round trip. Transforms apps into highly interactive, browser-based apps with no server dependency for UI processing after the app is loaded.

• Cross-Platform and Device Compatibility: Runs on any browser and platform without installation which makes it great for distributed or remote users. The app can also work without a connection after the initial load.

• Server Friendly: Offloads processing to the client. The server primarily serves static files, minimizing server maintenance.

While that may sound dreamy, there are some downsides to using WASM as well:

• Larger Initial Load Time: WASM downloads the entire app (including .NET runtime) on startup, which can be slow for large apps.

• Client Side Resource Dependency (Browsers): Requires modern browsers and reasonably powerful client devices to perform well.

How do Rendering Modes Come Into Play?

Rendering modes in Blazor define how components are rendered and made interactive, complementing the hosting models (Blazor Server or WebAssembly). They can prerender static HTML for SEO, enable interactivity on the server (Blazor Server), or run fully client-side (Blazor WebAssembly). Modes like Interactive Auto combine server-side rendering for fast initial load with client-side interactivity for the best of both worlds, tailoring the app's behavior to the hosting model's strengths and weaknesses.

Here’s an overview of rendering modes in Blazor:

To apply a render mode to a component, use the @rendermode directive in the component's Razor file. For example:

<YourComponent @rendermode="InteractiveServer" />

This directive specifies that YourComponent should use the Interactive Server render mode.

Blazor Server benefits most from rendering modes that optimize SEO or reduce latency for interactivity.

Blazor WebAssembly benefits from rendering modes that provide prerendering for SEO while retaining its client-side strengths.

The Ultimate Showdown: Blazor Server vs. WebAssembly

Now that you know the pros can cons of both Blazor Server and WebAssembly, which one do you choose for your project?

The Answer: It depends. Yeah, I know this is a cliche answer but it’s true and it is mostly dependent on the nature of your application and your business needs. 

You Should Use Blazor Server if you have:

• Internal Business Tools:
  • Inventory management or CRM applications where a stable network and centralized logic are feasible.
  • Example: A company-facing admin dashboard for tracking operations.

• Real-Time Collaboration:
  • Apps requiring frequent updates or multi-user synchronization.
  • Example: A real-time customer support chat or collaborative document editor.

• Resource-Constrained Clients:
  • Applications for older devices that can’t handle WASM’s client-side resource needs.
  • Example: A simple kiosk application for data entry in a controlled environment.

You Should Use Blazor WASM if you have:

• Distributed Enterprise Applications:
  • A sales tool for a remote workforce that can operate offline (e.g., updating product catalog offline, syncing later).
  • Example: A field engineer’s tool for diagnostic data that needs local processing.

• Customer-Facing Applications:
  • E-commerce portals or interactive dashboards requiring high responsiveness.
  • Example: An analytics dashboard providing real-time visualizations with minimal server interaction.

• Cross-Platform Migration:
  • Migrating a WinForms app for a broader audience using browsers on any device.

Need More Help Deciding?

If you’re still unsure which hosting model to use for your application, we can help you out! Our WebMAP for Blazor conversion tool can automate your code migration from WinForms/Desktop C# to Blazor - via both Blazor Server AND Blazor WASM.

Feel free to contact us with any questions regarding Blazor or migrating to Blazor.