Blazor – first impressions

What is Blazor?

To quote the official Blazor homepage

”Blazor is a single-page web app framework built on .NET that runs in the browser with WebAssembly.”

The natural follow-up question is then ”What is WebAssembly?”. From the official WebAssembly homepage we can read that

”WebAssembly (abbreviated Wasm) is a binary instruction format for a stack-based virtual machine. Wasm is designed as a portable target for compilation of high-level languages like C/C++/Rust, enabling deployment on the web for client and server applications.”

That is a very technical description, most likely formulated by a software engineer. I will make an attempt to describe Blazor and WebAssembly in my own words.

Blazor is a framework for building applications for the web, similar to AngularJS and React. However, Blazor makes it possible to write your applications in a .NET language, such as C#, instead of JavaScript. Since the JavaScript engines in the browsers are limited to executing JavaScript another solution is required for running compiled programs in binary format. This new format is called WebAssembly, Wasm, and is supported by Chrome, Edge, Firefox, and Safari.

Part of the Blazor project is to create a .NET Runtime in the Wasm format that runs in the browser and executes .NET bytecode.

Why Blazor over AngularJS or React?

Currently Blazor is still experimental so you should not use it in live products, yet. However, when it reaches a more stable state it should make a pretty awesome alternative to the JavaScript based frameworks. If you already write your Middleware and Backend code using .NET or .NET Core than it should be appealing to be able to use C# for the front-end as well, being able to go full stack using C#.

Another big thing is that compiled binary code in WebAssembly executes up to 5-10 times faster than JavaScript. In a time where JavaScript performance is becoming a bottleneck for web applications this is major deal.

Then there are a bunch of other things that makes it appealing to run .NET in the browser, like great development tools, well known APIs and stable build tools.

How is it to develop with Blazor right now?

I set up Blazor and went through a couple of tutorials and I must say that it feels really stable and performant already, even though it is still at an experimental stage. Being a .NET developer spending most of my time writing code in C# it felt really nice to be able to use that instead of JavaScript. Even though JavaScript is perfectly fine and I have nothing against developing in JavaScript if the job requires it, I feel a lot more comfortable with C# so it’s nice to be able to write both the backend code and the frontend code using C#.

When you create your web application with Blazor you create components which are HTML and C# code that you can either choose to display separately or as part of other components. The concept is easy to grasp and if you are comfortable working with HTML and C# you should be able to understand what’s going on in the code right away.

If you are a C# developer interested in web development I highly recommend that you give Blazor a try. My guess is that it will become one of the major web frameworks for creating Single Page Applications (SPA).

How can I get started?

Visit the official Blazor web site at where you will find instructions on how to get started as well as a tutorial that will guide you through the basic concepts.

You may also want to visit the official WebAssembly homepage at to learn more about Wasm.

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