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.

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](🔗) for package and version information.
## Install
Installed through [NuGet](🔗).
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 `PdfFile
` media implementation in the Optimizely package is used but in this case, 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:
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.