Supported file types for previews, thumbnails, and streaming

The Sync.com web panel and mobile apps include built-in previews, making it easy to view documents directly in Sync, without having to download, open, or share them to third-party preview apps.

In this article:


Web panel previews 

Sync lets you preview a wide range of file formats directly in your browser. Previews appear when you click a supported file in the web panel or open a shared link. This section focuses on supported web-based previews only. Mobile preview support may differ, as it depends on built-in functionality provided by iOS and Android.

Screenshot 2025-06-26 at 14.54.44.png

Notes:

  • Document previews supported files up to 40 MB in size.
  • The maximum file size supported for web-based editing is 50 MB for .docx, 5 MB for .xlsx and 300 MB for .pptx.
  • Free and Basic Sync plans are limited to .jpg, .gif, .png, and .txt.
  • Sync previews are shown in a bandwidth-saving, print-preview quality. Sync does not alter or compress your files in any way; photos are stored exactly as they are uploaded.
Format File Extension(s)
Supported Document Formats
Adobe Portable Document Format .pdf
Microsoft Word Format .doc, .dot
Microsoft Word Open XML Format .docx, .docm, .dotx, .dotm
Rich Text Format .rtf
Microsoft Excel Format .xls, .xlt
Microsoft Excel Open XML Format .xlsx, .xlsm, .xltx, .xltm
Microsoft PowerPoint Format .ppt, .pot, .pps
Microsoft PowerPoint Open XML Format .pptx, .pptm, .potx, .potm, .ppsx, .ppsm
OpenDocument Text Format .odt, .ott, .fodt
OpenDocument Spreadsheet Format .ods, .ots, .fods
OpenDocument Presentation Format .odp, .otp, .fodp
OpenDocument Math Formula Format .odf
OpenDocument Drawing Format .odg, .otg, .fodg
AutoDesk AutoCAD Format (v2.5 through 2014) .dwg, .dxf
AutoDesk Design Web Format .dwf
MicroStation Drawing Format (V7 and V8) .dgn
HyperText Markup Language Format .html, .htm
Extensible HyperText Markup Language Format .xhtml, .xhtm
Microsoft Outlook Format .msg
Outlook Express Email Format .eml
Text Format .txt
Comma-Separated Values Format .csv
Digital Imaging & Communication in Medicine Format .dcm, .dicom, .dcim, .dicm
Supported Image Formats
Tagged Image File Format .tif, .tiff
JPEG File Interchange Format .jpg, .jpeg
JPEG 2000 File Format and Code Stream .jp2, .jpc
Graphics Interchange Format .gif
Portable Network Graphics Format .png
Adobe Photoshop Format .psd, .psb
Microsoft Windows Bitmap Format .bmp, .dib
Macintosh Metafile Format .pct, .pic, .pict
Windows Metafile Format (Windows only) .wmf
Enhanced Metafile Format (Windows only) .emf
ZSoft Paintbrush PCX Format .pcx
ZSoft Paintbrush DCX Format .dcx
Sun Raster Data Format .ras
Kodak Photo CD Format .pcd
Truevision Targa Format .tga, .tpic
Continuous Acquisition and Life-cycle Support Format .cal, .cals
Icon Resource Format .ico
Windows Cursor Format .cur
NCR Image Format .ncr
X Window Dump Format .xwd
Silicon Graphics Image Format .sgi
Wireless Bitmap Format .wbmp
Scitex Color Tone Format .sct
WordPerfect Graphics Metafile Format .wpg
X Bitmap Format .xbm
Portable Bitmap Format .pbm
Portable Graymap Format .pgm
Portable Pixmap Format .ppm
Xerox 9700 Graphic Format .img
Dr. Halo Format .cut

Web panel and mobile thumbnails

Sync displays thumbnail previews for many common file types in both the web panel and mobile app file listings. If a thumbnail isn’t available, a generic file type icon will appear instead. 
Screenshot 2025-06-26 at 14.51.37.png

Notes:

  • Thumbnail support is more limited than full file previews. Certain file formats will not have thumbnails, but will display a full file preview when opened. Additionally certain file formats may appear only on mobile or web (these are listed as partial).
  • For supported file formats, thumbnails are generated for files up to 40 MB in size. For files sizes below 250KB the original file is inserted as the thumbnail.
Format File Extension(s)
Supported thumbnail formats: 
Portable Network Graphics Format .png
Bitmap Image Format .bmp (partial)
Portable Document Format .pdf (partial)
Tagged Image File Format .tiff (partial)
Tagged Image File Format .tif (partial)
JPEG Image Format .jpg
JPEG Image (Large, 29MB) .jpg (partial)
Graphics Interchange Format .gif
Icon Format .ico (partial)
WebP Image Format .webp
High Efficiency Image Format .heif (partial)
High Efficiency Image Coding .heic (partial)
QuickTime Movie .mov (partial)
MPEG-4 Video .mp4 (partial)

 


Web panel and mobile streaming (video & audio)

Sync features a built-in media player that lets you stream media files directly from the web panel or mobile app, no downloading required. 

Screenshot 2025-06-26 at 15.07.41.png

Notes:

  • Media files are streamed in their original quality, as Sync does not re-encode or transcode them in any way.
  • Streaming is not available on Free and Basic plans.
  • For supported plans, video files must be at least 6 MB and up to 20 GB in size to stream reliably.
Format File Extension Web Panel iOS (WiFi Only) Android
Support Video Formats:
MPEG-4 Video .mp4 Yes Yes Yes
QuickTime Movie .mov Safari / Firefox Yes Yes
Audio Video Interleave .avi Safari / Firefox Yes -
MPEG Video .mpg - Yes Yes
DVD Video Object .vob - Yes -
Support Audio Formats:
MPEG Audio Layer III .mp3 Yes Yes Yes
MPEG-4 Audio .m4a - Yes Yes
Advanced Audio Coding .aac - Yes -
Dolby AC-3 Audio .ac3 - Yes -
Free Lossless Audio Codec .flac - Yes -
Audio Interchange Format .aiff - Yes -
Enhanced AC-3 .eac3 - Yes -
Waveform Audio File .wav - Yes Yes
Ogg Vorbis .ogg - - Yes
MPEG Audio Layer II .mp2 - Yes -

 


How do document previews work?

  • For images, the Sync apps generate and encrypt a separate preview file locally when you upload the file.
  • For PDF documents, encrypted file data is downloaded directly into the browser and decrypted locally in your web browser.
  • For document formats the encrypted file data is downloaded directly into the browser and decrypted in real-time, then re-encrypted and streamed through an automated Sync helper server to generate a preview or securely passed to Microsoft's previewer / editor if that feature is enabled. Sync does not store this data.
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