---
title: Optimizely PDF Preview
slug: cms-12/docs/optimizely-pdf-preview
docTags: 
createdAt: 2026-08-10T15:56:04.000Z
---

When accessing the edit view in Optimizely Content Management System (CMS), you can select a PDF document from a media folder, to preview its content.

![](https://api.archbee.com/api/optimize/BrbvVORKJ5iIeSMZye5kI/8lBcbxoBrScnQIHLQKKLX_22ef356-pdf-preview.png)

In the `PdfPreview` package, there is a class named `PdfFile` which handles uploaded files with the .pdf extension.

## Requirements

- No additional license fee for the add-on.
- An Optimizely Content Management System (CMS) website with the *EPiServer.PdfPreview* package installed.
- See [Add-ons platform compatibility](docId\:qlMSwdEfyS4CJlGWdudqk) for package and version information.

## Installation

- Installed through [NuGet](https://nuget.optimizely.com).

PDF Preview is useful for websites where you manage multiple content items in PDF format.

## User scenarios

These are the typical user scenarios for adding PDF preview to your solution.

### The system does not have a model for handling PDF files

If the system does not have a model for handling PDF files, the default `PdfFile` model provided by the package is used. Editors can now preview PDF files in edit view without any extra steps.

### The system already has a model for handling PDF files

By default, the `ContentMediaResolver` class from CMS Core gets the first matching media implementation type registered for an extension. If there is an existing type registered for “pdf,” the `PdfFileMedia` implementation in the Optimizely package is used, but the existing type should be chosen in this case.

To change this default behavior, a media resolver class named `PdfContentMediaResolver` is used to ignore the `PdfFile` type in the Optimizely package, and thus, the existing registered media type is the candidate.

`PdfContentMediaResolver` inherits `ContentMediaResolver` and overrides the Type `GetFirstMatching(string extension)` method to handle the business logic above.

To turn on the PDF preview, the PDF media model must implement the `IPdfFile` interface. For example:

```csharp
[ContentType(DisplayName = "PdfFile", GUID = "…", Description = "")]
[MediaDescriptor(ExtensionString = "pdf")]
public class PdfFile: MediaData, IPdfFile {}
```

:::hint{type="info"}
**Note**
Due to limitations, after installing the add-on, you can preview only newly uploaded PDFs. You must upload existing PDFs again to be previewed.
:::