Lowercase URLs in C# MVC

Lowercase URLs are common with APIs. They can also be done in MVC applications. To some systems, URLS that are upper case or title case are treated as a different page in comparison to those that have only lower case URLs.

By default, C# MVC and API will used title cased URLs. Meaning the URLs will have a combination of upper and lower case letters in them. For systems that you are running internally, this probably won't be a big deal.

For those that are accessed by the public internet, it is a big deal because it can SEO implications.

SEO Reasons

In regards to SEO (Search Engine Optimization), URLS with upper case letters can be seen as a different URL than one with only lower case letters. The problem with this is that when two different URLs display the same content, search engines often consider that to be duplicate content. Because it is considered duplicate content, the search engine algorithm could derank your website or that page in the search results. That is not what you want to have happen.

Implementation

To implement this throughout your entire application, you can use the below in your Program.cs file.

NOTE: At the time of writing this article, .NET 10 is the current and latest stable version. Thus the code is written for this version and may not work in future versions.

builder.Services.Configure<RouteOptions>(options =>
{
    options.LowercaseUrls = true;
    // options.LowercaseQueryStrings = true;
});

The LowercaseUrls option will make the URLS lower cased, even when entered as upper or title case. I would also make sure that the links within your application are always lower cased.

The LowercaseQueryStrings option will enforce that the query parameters also be lowercased. If using case-sensitive parameters, this option should be disabled.