Previewing Images and Documents


The Files.com web interface supports previewing images, office documents, and text documents. This allows users to verify the contents of a file without extra the steps of downloading the document and opening it in an external program.

Previewing is also 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 even choose to restrict visitors so they can only preview files within the link but not download them to their own device.

Supported Image File Types

Image preview and image rotation functionality are available for the following image types:

.4fr.aai.ai
.art.arw.avs
.bmp.cgm.cin
.cip.cr2.crw
.dcm.dcr.dcx
.dib.dpx.ept
.fax.gif.gv
.heic.heif.ico
.icon.jng.jp2
.jpg.jpeg

New files types are always being added to our File Preview compatibility list. Check here often to see what has been added.

Supported Text File Types

You can preview many types of text based documents, such as source code files, structured data files, unformatted text files, and markdown files. Source code files include syntax highlighting for most language types.

File TypeExtensions Supported
Structured data files
.xml
.json
Unformatted text files
Markdown files
.md
.markdown
.mdown
.mkdn

Additional Text File Extensions

Site administrators can customize your site's Viewer & Editor settings to supply additional file extensions that should use the text previewer.

One common reason to enable this option is to prevent automatically converting a delimited file, such as CSV, to a spreadsheet file. You might choose to view CSV files directly within files without converting to avoid problems with large numbers or non-standard date formats.

Another reason to add an extension to your previewer is when a system produces plain text files with a nonstandard extension. For example, if you transfer a delimited text file for invoices that ends in the extension ".inv", you wouldn't be able to preview those files without adding the extension to your site's settings.

Supported Source Code Languages

Our previewer supports over 280 programming languages' associated files. If you're using standard extensions for your source files, you will almost assuredly be able to preview those files within Files.com with automatic syntax highlighting.

For source code files that do not use a standard extension, you can add that extension as a custom text file extension for your site. This will allow you to preview the files within Files.com, but will not include automatic syntax highlighting.

Supported Office Document Types

By default, your site will be configured to use the Files.com editor for previewing Office documents. A site administrator can choose which type of office document to enable for all Office documents: the Files.com editor, Microsoft Office for Web, or disabling entirely.

When integrations for editing Office documents have been disabled, the previews will be generated as PDF files, which can result in some unexpected formatting.

Some older office document formats, such as .doc, .xls and .ppt will require conversion before they can be displayed. This can also cause unexpected formatting changes.

Files.com Editor Supported File Types

File TypeExtensionsExtensions Needing Conversion
Document.docx
.docxf
.djvu
.doc
.docm
.dot
.dotm
.dotx
.epub
.fb2
.fodt
.htm
.html
.mht
.mhtml
.odt
.ott
.oxps
.rtf
.stw
.sxw
.wps
.wpt
.xps
Spreadsheet.xlsx
.xltx
.csv
.et
.ett
.fods
.ods
.ots
.sxc
.xls
.xlsm
.xlsb
.xlt
.xltm
Presentation.pptx
.potm
.ppsx
.dps
.dpt
.fodp
.odp
.otp
.pot
.potx
.pps
.ppsm
.ppt
.pptm
.sxi

Microsoft Office for Web Supported Documents

File TypeExtensionsExtensions Needing Conversion
Word.docx.doc
.docm
.dot
.dotx
.dotm
.odt
Excel.xlsx
.xlsm
.xlsb
.xls
.xla
.ods
.csv
.xml
.xmlx
.mht
.mhtml
.htm
.html
.dif
.slk
.xps
PowerPoint.pptx
.ppsx
.ppt
.pot
.potm
.potx
.pps
.ppsm
.pptm
.odp

PDF Preview Limitations

Files.com offers a built-in PDF viewer for previewing PDF documents. This PDF viewer does not fully support all capabilities of PDFs. Specifically, it does not support fillable forms or embedded PDF documents. Additionally, certain rendering issues may occur with certain PDF files.

Our PDF viewer is built using a 3rd party PDF engine called PDF.js. Due to the 3rd party nature of the viewer, we aren't able to accept bug reports that relate to PDF rendering. If you need to view fillable form data, or if a PDF isn't previewing perfectly, please download the PDF and view it locally.

We are tracking customer interest in a more sophisticated PDF engine, and we may consider changing PDF engines in the future. If you have a specific example of a PDF that you use in your business that cannot be viewed in our existing PDF viewer, please send it to us so we can add it to the improvement request we are tracking.

Interactions With Other Files.com Features

In order to render image and PDF 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. Because of that, a logged-in user must have Read permissions in order to preview.

Web Interface File Listing

The Files.com web interface includes inline previews for the Thumbnail and Grid listings of image, pdf and document files. Users who do not have Read permissions cannot 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.

File Listings 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 Remote Server 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 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 office documents 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.

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