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ASU Digital Repository

Recommended File Formats

File formats are standard ways that information is encoded for storage in a digital computer file. The standards specify how bits are used to encode information, and they tell software programs how to display its contents.

ASU's institutional repository, KEEP, accepts digital files in any format. However, we strongly encourage those depositing files to consider the sustainability of the file formats that they wish to deposit. Over time, software applications and specifications used to open and interpret files become harder to find, rendering some formats difficult or impossible to read in the future.

The long-term preservation of digital materials is more easily achievable if you try to adhere to the following guidelines. Try to select file formats that:

  • are non-proprietary and are openly documented;
  • are high-quality;
  • are uncompressed and unencrypted;
  • are representative for your discipline, and are in relatively wide use;
  • do not contain embedded files, programs, or scripts;
  • is not controlled by DRM (digital rights management) software.

ASU Library is committed to preserving the binary form of deposited materials and takes measures to preserve the look and feel of deposited digital objects, as resources permit. This may involve migrating files to open and accessible file format standards, or utilizing emerging technology such as emulation, when necessary.

Using highly-recommended formats improves the likelihood that the materials will remain accessible long-term.

  • High recommended formats have the most support and the highest probability of long-term access and preservation. The formats are widely used, openly documented and uncompressed (or have lossless data compression.)
  • Medium identified formats do not meet the current minimum international standards for long-term retention but are widely adopted and more likely to be manageable for long-term access.
  • Low identified formats are not recommended and may not be supported for long-term access. These files require evaluation by library staff. Please contact us for assistance.

The recommended file formats chart is not an exhaustive list. Please contact us if you have any questions concerning preparing your files for deposit. 

Recommended File Formats
File Type High Moderate Low
  • AIFF (.aiff, .aif),
  • Broadcast WAV (.bwav and .wav),
  • WAV (.wav)
  • Advanced Audio Coding (.aac, .m4a, .mp4),
  • Apple Lossless Audio Codec (.mp4),
  • Audio Interchange File Format (uncompressed) (.aif, .aiff),
  • Free Lossless Audio Codec (.flac),
  • Moving Picture Experts Group 3 (.mp3),
  • Standard MIDI (.mid, .midi)
  • AIFC-compressed AIF (.aifc),
  • Apple Protected (.m4a),
  • Extended MIDI (.xmi),
  • iTunes (.aac),
  • Module Music Formats (.mod),
  • QuickTime MP4 Protected (.m4p, .m4b),
  • QuickTime MP3 (.m3p),
  • Ogg Vorbis (.ogg),
  • RealAudio (.rm, .ra),
  • RIFF-RMID (.rmi),
  • Windows Media Audio (.wma)


(vector images)

  • Open Document Graphics (.odg)
  • PDF/A-1 - ISO 19005-1 (.pdf)
  •  Scalable vector graphics (.svg)

  • Computer graphics metafile (.cgm)
  • Illustrator document (.ai)
  • Photoshop document (.psd)
  • Encapsulated Postscript (.eps)
  • Macromedia Flash (.swf)
  • All other image formats not listed here
Moving Image
  • FFV1/Matroska (.mkv)
  • AVI - uncompressed (.avi)
  • QuickTime - uncompressed, motion JPEG (.mov)
  • Digital Picture Exchange (.dpx)
  • Motion JPEG 2000 (.jp2)
  • MPEG-1, MPEG-2 (.mp1, .mp2)
  • Ogg Theora (.ogg)
  • MPEG-1, MPEG-2 (.mpg, .mpeg, wrapped in AVI, MOV)
  • MPEG-4 (H.263, H.264) (.mp4, wrapped in AVI, MOV)
  • Windows Media Video (.wmv)
  • RealVideo (.rm, .rv)
  • Flash Video (.flv, .f4v)
  • presentation">MPEG-4 ASP (Divx, Xvid) (.avi)
  • MPEG-4 H.264 (DRM protected) (.m4v, .mp4)
  • all others
  • PDF/A-1 --  ISO 19005-1 (.pdf)


  • Microsoft Powerpoint 2007+ (OOXML) (.ppt, .pptx),
  • OpenDocument Presentation (.odp)
  • Portable Document Format (.pdf)
  • PowerPoint (.ppt)
  • Keynote (.key)
  • Comma- or tab-separated Values (.csv, .tsv, .txt)
  • Delimited text
  • Open Document Spreadsheet (.ods)
  • OOXML (ISO/IEC DIS 29500) (.xlsx)
  • Excel 2007 or newer (.xlsx)
  • OpenOffice (.sxc/.ods)
  • DBF (.dbf)
  • Excel 2003 or older (.xls)
  • All other spreadsheet/ database formats not listed

Still Image


  • TIFF - uncompressed or CCITT 4 compressed (.tiff)
  • JPEG2000 - lossless compression (.jp2, .jpx)
  • PNG (.png) - 24bit true color
  • JPEG (.jpg, .jpeg)
  •  JPEG2000 lossy compressed (.jp2, .jpx)
  • PNG (.png) - 8 bit indexed
  • TIFF lossy compressed (.tif, .tiff)
  • GIF (.gif)
  • Photoshop document (.psd) RAW files


  • All other image formats not listed here
Structural Markup
  • Standard Generalized Markup Language with DTD/Schema (.sgml),
  • XML with DTD/Schema (.xml)
  • Standard Generalized Markup Language without DTD/Schema (.sgml),
  • eXtensible Markup Language without DTD/Schema (.xml)
  • UTF-8 Unicode text (.txt)
  • Open Document text (.odt)
  • PDF/A (.pdf)
  • XML with included schema (.xml)
  • PDF (.pdf) (embedded fonts)
  • Rich Text Format (.rtf)
  • HTML (include a DOCTYPE declaration) (.html)
  • Microsoft Word 2007 or newer (*.docx)
  • Cascading Style Sheets (.css)
  • Document Type Definition (.dtd)
  • PDF (.pdf) (encrypted)
  • Microsoft Word 2003 or older (.doc)
  • WordPerfect (.wpd)
  • Pages (.pages)
  • All other text formats not listed
Virtual Reality
  • X3D (.x3d)
  • VRML (.wrl, .vrml)
  • U3D (Universal 3D file format)
  • all others
  • Web ARChive (.warc)
  • Hypertext Markup Language (.html)


The ASU Library acknowledges the twenty-three Native Nations that have inhabited this land for centuries. Arizona State University's four campuses are located in the Salt River Valley on ancestral territories of Indigenous peoples, including the Akimel O’odham (Pima) and Pee Posh (Maricopa) Indian Communities, whose care and keeping of these lands allows us to be here today. ASU Library acknowledges the sovereignty of these nations and seeks to foster an environment of success and possibility for Native American students and patrons. We are advocates for the incorporation of Indigenous knowledge systems and research methodologies within contemporary library practice. ASU Library welcomes members of the Akimel O’odham and Pee Posh, and all Native nations to the Library.