Setting up multilingual MVC projects

To serve content in multiple languages on MVC sites, you first need to set up functionality that detects and sets the current culture for each request. You can then localize the content displayed on the site's pages.

If you want to have a multilingual MVC site, you need to set up culture recognition in the MVC project. On the beginning of every request, you need to:

  1. Retrieve or determine the correct culture to be used in the current request. The way you detect the culture depends on the implementation of your multilingual site. For example, possible options are culture prefixes in URLs, culture-specific domains, custom cookies, etc.
  2. Set the Thread.CurrentThread.CurrentUICulture and Thread.CurrentThread.CurrentCulture properties of the current thread (available in the System.Threading namespace).

    Note: Thread.CurrentThread.CurrentUICulture and Thread.CurrentThread.CurrentCulture are properties of the .NET framework and use the System.Globalization.CultureInfo type. They are not directly comparable with the Kentico CMS.Localization.CultureInfo type, or the CurrentUICulture and CurrentCulture properties of the CMS.Localization.LocalizationContext class.

The Kentico localization API then automatically works with the given culture (for example when resolving resource strings).


One common way to determine the culture of page requests is to use culture prefixes in your site's routes. For example:

  • English – www.example.com/en-us/path
  • Spanish – www.example.com/es-es/path

The following code examples showcase how to parse the culture from the route prefix and set the current culture for the MVC application. You can modify and adjust snippets from this example for use in your own projects.

Example - RouteConfig
using System.Web.Mvc;
using System.Web.Routing;


public static void RegisterRoutes(RouteCollection routes)

    // Parses a URL containing a culture route prefix
    var route = routes.MapRoute(
        name: "Default",
        url: "{culture}/{controller}/{action}",
        defaults: new { controller = "Home", action = "Index" },
        constraints: new { culture = new SiteCultureConstraint() }

    // Assigns a custom route handler to the route
    route.RouteHandler = new MultiCultureMvcRouteHandler();
Example - MultiCultureMvcRouteHandler
using System.Globalization;
using System.Threading;
using System.Web;
using System.Web.Mvc;
using System.Web.Routing;

public class MultiCultureMvcRouteHandler : MvcRouteHandler
    protected override IHttpHandler GetHttpHandler(RequestContext requestContext)
        // Retrieves the requested culture from the route
        var cultureName = requestContext.RouteData.Values["culture"].ToString();
            // Creates a CultureInfo object from the culture code
            var culture = new CultureInfo(cultureName);

            // Sets the current culture for the MVC application
            Thread.CurrentThread.CurrentUICulture = culture;
            Thread.CurrentThread.CurrentCulture = culture;
            // Handles cases where the culture parameter of the route is invalid
            // Returns a 404 status in this case, but you can also log an error, set a default culture, etc.
            requestContext.HttpContext.Response.StatusCode = 404;

        return base.GetHttpHandler(requestContext);
Example - SiteCultureConstraint
using System.Web;
using System.Web.Routing;

using CMS.SiteProvider;

// Constraint that restricts culture parameter values
// Only allows the codes of cultures assigned to the current site in Kentico
public class SiteCultureConstraint : IRouteConstraint
    public bool Match(HttpContextBase httpContext,
                    Route route,
                    string parameterName,
                    RouteValueDictionary values,
                    RouteDirection routeDirection)
        string cultureCodeName = values[parameterName]?.ToString();
        return CultureSiteInfoProvider.IsCultureOnSite(cultureCodeName, SiteContext.CurrentSiteName);

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