How to use asp net mvc 4 to bundle less files in release mode


ASP.NET is a popular language used for building web applications. One of the key features of ASP.NET is its ability to bundle and minify static files, such as CSS and JavaScript, to improve performance and reduce the number of HTTP requests made by the browser. In this article, we will explore how to use ASP.NET MVC 4 to bundle Less files in release mode.

What is Less?

Less is a dynamic stylesheet language that extends CSS with features like variables, mixins, and functions. It makes writing and maintaining CSS code easier and more efficient. Less files have a .less extension and need to be compiled into CSS before they can be used in a web application.

Setting up the ASP.NET MVC 4

To get started, a new ASP.NET MVC 4 project in Visual Studio. Make sure you have the necessary prerequisites installed, such as the .NET Framework and the ASP.NET MVC 4 framework.

Installing the LessBundle

In order to bundle Less files in ASP.NET MVC 4, we need to install the LessBundle NuGet package. Open the NuGet Package Manager Console in Visual Studio and run the following command:

Install-Package dotless

This will install the dotless compiler, which is used to compile Less files into CSS.

Creating a Less bundle

Once the LessBundle package is installed, we can create a new bundle for our Less files. Open the BundleConfig.cs file in the App_Start folder and add the following code:

using .Web.Optimization;

public class BundleConfig
    public static void RegisterBundles(BundleCollection bundles)
        bundles.Add(new LessBundle("~/bundles/less").Include(

In this code, we are creating a new bundle named “less” and including the main.less file located in the Content/less folder. You can include multiple Less files in the bundle by adding additional paths to the Include method.

Enabling bundling and minification

In order to enable bundling and minification in ASP.NET MVC 4, we need to the BundleConfig.cs file again. Add the following code to the RegisterBundles method:

BundleTable.EnableOptimizations = true;

This line of code enables bundling and minification for all bundles defined in the application.

Using the Less bundle in a view

Now that we have created a Less bundle, we can use it in our . Open the _Layout.cshtml file in the Views/Shared folder and add the following code:


This code will render the bundled and minified CSS from the Less files in the specified bundle. Make sure to place this code inside the head section of your HTML document.


In this article, we have learned how to use ASP.NET MVC 4 to bundle Less files in release mode. By bundling and minifying our static files, we can improve the performance of our web applications and reduce the number of HTTP requests made by the browser. ASP.NET MVC 4 provides a convenient way to bundle Less files using the LessBundle NuGet package. By following the outlined in this article, you can easily incorporate Less into your ASP.NET MVC 4 .

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