# Markdown to HTML Conversion

Umbraco requires Markdown to be converted into HTML. Primarily, this is to support the [Markdown property editor](/umbraco-cms/18.latest/model-your-content/property-editors/built-in-umbraco-property-editors/markdown-editor.md). There are also internal use cases, for example, in rendering email notification content for [health checks](/umbraco-cms/18.latest/run-in-production/infrastructure-and-ops/health-check.md).

The conversion is managed via the `IMarkdownToHtmlConverter` interface.

Umbraco registers a default implementation of `MarkdigMarkdownToHtmlConverter`, which is based on the [`Markdig` library](https://github.com/xoofx/markdig).

Also provided is an unregistered, alternate implementation of `HeyRedMarkdownToHtmlConverter`, based on the [Hey Red Markdown library](https://github.com/hey-red/Markdown). This implementation is deprecated and will be removed in Umbraco 19.

Both implementations convert standard markdown into HTML, but there are some subtle differences in the output produced.

## Modifying the Default Behavior

If you prefer to use the Hey Red-based implementation, replace the default registration by adding the following composer:

```csharp
using Umbraco.Cms.Core.Composing;
using Umbraco.Cms.Core.Strings;
using Umbraco.Cms.Infrastructure.Strings;

public class MarkdownToHtmlComposer : IComposer
{
    public void Compose(IUmbracoBuilder builder)
    {
        builder.Services.AddUnique<IMarkdownToHtmlConverter, HeyRedMarkdownToHtmlConverter>();
    }
}
```

Alternatively, the interface itself can be implemented directly, enabling you to use the library and custom behavior you prefer:

```csharp
namespace Umbraco.Cms.Core.Strings;

public interface IMarkdownToHtmlConverter
{
    /// <summary>
    /// Converts the specified Markdown-formatted text to an HTML-encoded string.
    /// </summary>
    /// <param name="markdown">The input string containing Markdown syntax to be converted.</param>
    /// <returns>A string containing the HTML representation of the input Markdown.</returns>
    public string ToHtml(string markdown);
}
```

## Planned Updates

The Hey Red Markdown library is deprecated. The `HeyRedMarkdownToHtmlConverter` implementation will be removed in Umbraco 19.


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