# What is WebAssembly?

> In this article I will try to answer the most common questions about WebAssembly. If you prefer the video format, a podcast is available here. What is WebAssembly?…

- Author: Jérôme Giacomini
- Language: en
- Canonical URL: [What is WebAssembly?](https://jeromegiacomini.net/articles/2018/09/21/what-is-webassembly)
- Published: 2018-09-21
- Last modified: 2026-09-05
- Topics: ASP.NET Core, .NET, C#, DevOps

In this article I will try to answer the most common questions about WebAssembly.

If you prefer the video format, a podcast is available [here](https://www.youtube.com/watch?v=lbmICsPjFw0).

![](https://jeromegiacomini.net/Blog/wp-content/uploads/2018/09/wa_logo.png)

## What is WebAssembly?

WebAssembly is a binary code standard that is understandable by modern browsers.

The pointy ones won't talk about byte code but dASTAST (Abstract Syntaxt Tree) but that's another debate.

## So WebAssembly is a new language?

No, it's a binary format like the assembler.

It was designed to be used with high-level languages like C/C++/Rust, C# to design web applications.

For example, for C# instead of producing IL it could create a binary WebAssembly.

## Do we need to generate a binary for every x86, x64 and ARM platform?

No, binary is platform-independent: there will be no specific compilation for ARM/x32/x64.

## Is this a company that creates WebAssembly?

No, it's the same consortium as HTML: the W3C.

What makes this initiative very interesting is that neither Adobe nor Microsoft are trying to impose a new binary format.

![](https://jeromegiacomini.net/Blog/wp-content/uploads/2018/09/w3c.png)

## Which browser supports this?

WebAssembly is supported by the four main browsers: Edge, Chrome, Firefox and WebKit.

And it's been that way since late 2017.

![](https://jeromegiacomini.net/Blog/wp-content/uploads/2018/09/allbrowsers.png)

## What are the advantages of WebAssembly over JavaScript?

The WebAssembly binary is already compiled when it reaches the browser:

Its parsing is very easy: according to recent experiments it would be 20 times faster than a JavaScript file

This is not a text file so it will be « minus  big

It is therefore faster to load and faster to execute.

It is also faster to perform calculations: it will therefore be more suitable for compression, image manipulation, video games...

## Is WebAssembly safe?

WebAssembly is in a secure sandbox running environment.It inherits the same security strategies as JavaScript.

## Is WebAssembly going to replace JavaScript?

![](https://jeromegiacomini.net/Blog/wp-content/uploads/2018/09/js.png)

WebAssembly is not intended to replace JavaScript. It is designed to complement JavaScript with superior performance. It is an alternative to building web applications or 2D/3D games, for which it is more optimized.

## Can WebAssembly communicate with JavaScript?

Yes, I did. **WebAssembly JavaScript Interface**, which provides an explicit JavaScript API to interact with WebAssembly.

## Is WebAssembly the new Flash / Silverlight / JavaFX?

WebAssembly has some similarity to these engines.

But unlike his elders:
- There is not a single big company trying to set its own standard.
- It's not a plugin to add to the browser, the engine is already integrated and functional in the web browser


![](https://jeromegiacomini.net/Blog/wp-content/uploads/2018/09/flashSLJavaFX.png)

## What tools can generate WebAssembly binaries?

In dotnet 3 tools allow to generate WebAssembly:

[Unity3D](https://blogs.unity3d.com/2018/08/15/webassembly-is-here/) : 2D and 3D video game engine

[Blazor](https://blazor.net/) The ASP.NET team has brought the Razor view engine into WebAssembly.

[Uno Platform: UWP everywhere](https://playground.platform.uno/): nventive allowed the UWP code to run on iOS/Android but also WebAssembly.

These three tools are still in beta on WebAssembly byte code generation, so we're going to have to wait a little longer before we start migrating our web applications to this new format.

Happy coding

## To go further:
- [Presentation of the Uno Platform](https://jeromegiacomini.net/Blog/2018/05/15/uwp-everywhere-uno/)