Documentation

Previewing Files

The Files.com web interface supports previewing a wide array of files, including images, business documents, text documents, and audio and video files. This allows users to verify a file’s contents without the extra steps of downloading it and opening it in an external program.

Previewing some types of files is supported for visitors to Share Links. Any Share Link that allows visitors to download will also include the option for visitors to preview supported file types. You can choose to restrict the allowed actions for a Share Link so visitors can only preview files within the link but not download them to their own device.

Required Permissions for Previewing

In order to render file previews within the Files.com web interface, the file contents are transferred to the user's browser and then rendered as a preview by that browser. The minimum permission required to preview files is List/Preview. Users with the Read permission or higher can also preview files. Users with only the List or Write permission cannot preview files.

List/Preview Permission

Users with the List/Preview permission can browse folders, see file names, and open previews for images, PDFs, business documents, audio, and video files. They cannot download the original file, upload, modify, delete, or share files. For these previewable file types, users see the rendered preview but the original file download is blocked. For all other file types, the file appears in the folder listing but cannot be previewed, opened or downloaded.

Users with the Read permission or higher can both preview and download files, including file types that are not previewable.

The List/Preview permission controls preview access through the Files.com Web App only. The Desktop App, Mobile App, FTP, SFTP, WebDAV, and the CLI do not offer preview-only access. Those clients and protocols continue to follow standard read permission behavior.

The List/Preview permission uses the same preview system already available across Files.com and does not change the behavior of existing permission levels like Read, Full, or Admin.

List/Preview Permission Is Not a Security Boundary

The List/Preview permission blocks normal file download and allows users to preview images, PDFs, business documents, audio, and video files in the web browser. It does not prevent content exfiltration through screenshots, screen recording, printing, copy/paste from previews, browser extensions or apps that capture or save rendered page content, browser developer tools, cached preview assets, or photographing the screen. It is not a substitute for DRM, data loss prevention (DLP), or information rights management (IRM) solutions.

If your use case involves image or PDF files, consider adding Watermarks to overlay identifying information on previews, which can discourage casual redistribution.

Thumbnails

Thumbnails are small preview images that represent files. These inline previews appear in Thumbnail and Grid views, and in the Metadata panel for image, PDF, and document files in the Files.com web interface and Desktop App mounted drive. Users must have at minimum the List/Preview or Read permission to see these inline previews.

Using the Thumbnail or Grid mode does not log any file transfers, and does not trigger any type of notifications or webhooks.

Files on Remote Server Mounts

In order to display inline previews for a folder on a Remote Server Mount, the Files.com platform must access the contents of the file in order to be able to display it. To save resources, Files.com uses an intelligent caching strategy, which prevents extraneous transfers for repeated viewing of a file that has not changed.

Viewing an inline preview is not considered a download by your site, and will not result in a download action logged, nor will it trigger any type of notification, automation or notification. However, the remote server may record the activity as a download, and it cannot distinguish between a transfer for creating previews or a transfer that is fetching the file. If the remote server automatically deletes files as soon as they are downloaded, consider using a Sync to copy the files to a folder that is not mounted, so that if your users preview files, it won't trigger an auto-deletion on the source system.

File History and Notifications

Previewing an image, PDF, audio, or video file will not result in a download action logged in the file history. The transfer of a file for previewing does not trigger any type of notifications or webhooks.

Previewing text documents (source code, structured data, markdown or text) is logged in the file history, and will trigger notifications or webhooks.

Previewing standard productivity suite format files also transfers the file from your storage to the editor in order to be previewed, but this activity will appear in your history with the interface "office." This transfer is logged, will trigger any type of notifications or webhooks.

Visitors to a Share Link that allows downloading see an interface that is similar to the Files.com web interface file listing, including the ability to see inline image and PDF previews.

When the default view the visitor first sees contains mostly preview-able files, the view mode will default to Grid mode; if less than half of the items the visitor sees when they open the link are preview-able, the listing will default to List mode. Visitors can switch at any time between List, Thumbnail and Grid mode for the listing.