# API Documentation

A library of API Reference documentation is auto-generated from the comments within the Umbraco Source Code.

## C# API Documentation

C# API references for the Umbraco Core, Infrastructure, Extensions, and Web libraries.

### [Umbraco.Cms.Core](https://apidocs.umbraco.com/v17/csharp/api/Umbraco.Cms.Core.html)

### [Umbraco.Cms.Infrastructure](https://apidocs.umbraco.com/v17/csharp/api/Umbraco.Cms.Infrastructure.html)

### [Umbraco.Cms.Web](https://apidocs.umbraco.com/v17/csharp/api/Umbraco.Cms.Web.Common.html)

### [Umbraco.Extensions](https://apidocs.umbraco.com/v17/csharp/api/Umbraco.Extensions.html)

{% hint style="info" %}
Opens a documentation browser that is different from the documentation section you're viewing now.
{% endhint %}

## Backoffice UI Documentation

You can find all reference documentation for the Backoffice UI in the [UI Library](https://docs.umbraco.com/umbraco-cms/customizing/ui-library) article.