File formats

All digital file formats risk becoming obsolete and falling out of use. If this happens, valuable research data could be lost because they can no longer be read or used. Therefore, it is important to choose file formats that are likely to remain usable in the future.

When selecting a file format, you should choose one or more formats that enable the reuse of the project’s research data in both the short and long term. In general, the most suitable formats for accessibility and long-term preservation are those that are widely used, well-documented, and open. This means that the format:

• is based on an open standard
• is independent of a specific platform or software
• is openly documented
• is kept by an independent organization.

The opposite of open file formats are proprietary file formats, which can usually only be opened with software developed by the format’s owner. If you primarily work with proprietary software and formats, the best approach may be to make data available in the standard format for your discipline while also providing data in a format more suitable for long-term preservation and accessibility beyond your field of research.

The most important aspect is to ensure that the files you save at the end of your research project can still be opened in the future. By using open, well-documented formats, you maximize the likelihood that files can still be read and used even if the software you originally used becomes obsolete.

If you work in a proprietary format and later convert files for accessibility and long-term preservation, it is recommended to save data both in the format you work with and simultaneously in an open format that is more suitable for sharing and long-term preservation.

When converting files to new formats, it is crucial to retain the original files to prevent data loss. Open formats recommended for preservation may not always retain all information present in proprietary formats. Read more about what to consider when converting files on the page Compression of audio, images, and video.

File formats for different types of data

On these pages, you will find recommendations for file formats suitable for data sharing, accessibility, and long-term archiving. The lists are continuously updated and do not represent a comprehensive catalogue of all file formats. If you need advice on suitable file formats for long-term preservation, contact your local research data supportOpens in a new tab.

• Text

  Learn more about how to create text files and documents that stay readable and shareable in the long term.

• Databases and spreadsheets

  Explore how to organize data in databases and spreadsheets, and what to consider to ensure your data stay usable and accessible to others.

• Spatial data (GIS)

  Spatial data describes objects with geographical properties such as position, size, or shape. Here you find information on suitable file formats for spatial data.

• Images

  Digital images exist in raster and vector formats. Raster images are highly detailed but lose quality when resized, while vector images can be scaled without quality loss.

• Photogrammetry

  Photogrammetry is a technique that uses photographs for measurements, such as finding the positions of geographical elements or creating 3D models.

• Digital audio

  To preserve digital audio in high quality, files should be uncompressed. Here you will find information on file formats and considerations for preserving and sharing audio files.

• Digital video

  Digital video is increasingly used to document research projects. This section provides advice on file formats, key features, and how to preserve and share video files for long-term use.

• Compression

  Compression of audio, images, and video affects file size and quality. Here you find guidance on when and how to compress files for sharing and long-term preservation, and information on file formats and codecs.

Working files

It is common for researchers to use file formats that are standard within their field but less commonly used elsewhere. You should select a format that suits your data collection and analysis methods, but it is worth checking in advance whether the format is also suitable for data sharing and long-term preservation. It is valuable if those who wish to reuse your data can open the files even without access to the specific software you used.

If it is not possible from the outset to use a format suitable for accessibility and long-term preservation, an alternative is to convert the files intended for preservation into a more suitable format. Document your choices in your project documentation, such as the data management plan, specifying which formats are used for which purposes, such as working with or sharing data. Always remember to save the original files to ensure that no information is lost!

Some data sources (machines, scanners, drones, etc.) have software that only allows data to be saved in the program’s proprietary format. This can make data less accessible and usable in the long term. Ideally, these programs should only be used for data that must be processed in this way. In such cases, it is advisable to follow the principle, “It is better to share what exists than not to share at all.” It may also be possible to provide proprietary data formats alongside open format files holding extracted data. Document both the software used for data collection and analysis, and the software version. 

If you develop your own analysis software, ensure that it can save data in a format readable without the software (e.g., an XML-based format). If this is not possible, at least enable data export to another file format, even if some information is lost. As mentioned earlier, always save and share original files to avoid the risk of data loss.