> For the complete documentation index, see [llms.txt](https://docs.umbraco.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.umbraco.com/umbraco-cms/13.latest/reference/api-documentation.md).

# API Documentation

Information on Umbraco 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/v13/csharp/api/Umbraco.Cms.Core.html)

### [Umbraco.Cms.Infrastructure](https://apidocs.umbraco.com/v13/csharp/api/Umbraco.Cms.Infrastructure.html)

### [Umbraco.Cms.Web](https://apidocs.umbraco.com/v13/csharp/api/Umbraco.Cms.Web.Common.html)

### [Umbraco.Extensions](https://apidocs.umbraco.com/v13/csharp/api/Umbraco.Extensions.html)

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## Backoffice UI API Documentation

Angular, JavaScript, CSS & Less UI API references for building Umbraco backoffice components.

* The umbraco.directives
* The umbraco.services
* The umbraco.resources

### [Backoffice UI](https://apidocs.umbraco.com/v13/ui/)

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