Using open, non-proprietary, well-documented, or widely used file formats is important for ensuring that research data remain accessible and usable in the future. These preferred file formats are ones that are most likely to offer the best long-term guarantees for usability, accessibility, and sustainability. If data are stored in non-preferred formats, there is a risk that users of your collection will not be able to open your data files because they have to pay for software to open the file or because this software no longer exists. The latter may also be a risk for you if you want to use your files in the future. Non-preferred formats also may not integrate well with other tools or workflows, and might lose relevant information when the file is migrated to another file format.
Preservation in the RDR
The RDR offers the highest level of preservation on preferred file formats listed in the table below. This means that the RDR strives to not only store the "bits" of the files, but to also ensure that the files remain accessible.
'Other sustainable formats' in the table below are widely used and therefore likely to remain accessible. However, the RDR does not offer active preservation activities on these files to keep them accessible. Using these formats is therefore riskier.
For file formats that are not listed in the table below (non-preferred file formats), the RDR does not make any statements about the associated risks nor offer active preservation activities. It is therefore not recommended to use these formats, however you are allowed to do so.
File format warning
If you upload a file in a format that is not in the table below, the RDR will show a warning symbol next to that file. We advise you to do the following:
- Change the file format to one that is in the table below, preferably a 'preferred format'. Please make sure that no information is lost as a result of this conversion.
- Choose a format that allows files to be opened with software that is commonly used in your research field and add a version of the file in a preferred or other sustainable format. That way, by storing the file in two different formats (including a preferred format), your collection is usable, accessible and sustainable, while also maintaining the non-preferred, but commonly used format of the original.
- If neither of the previous options is feasible, you can accept the risk that your collection might currently be, or in the future become, less usable, accessible or sustainable. Know that the RDR does not offer active preservation activities on this case and therefore does not recommended this option.
Compressed files (e.g. .zip or .tar) are not in the preferred format lists, because the system itself already compresses files so there are few additional gains in size to be made. Furthermore, it makes the collection less reusable and accessible, because the files need to be unpacked before use.
Format listing
| Type | Preferred format | Other sustainable formats |
|---|---|---|
| Audio | OGG (.ogg), BWF (.bwf), FLAC (.flac), Wave / WAV (.wav) | MP3 (.mp3) |
| CAQDAS (Computer Assisted Qualitative Data Analysis) | RTF (.rtf) | Some software-specific formats such as NUD*IST, Nvivo, ATLAS.ti |
| Code and analysis scripts | MATLAB (.m), Python (.py), R (.R), SPSS (.dat/.sps), STATA (.dat/.do) | SPSS portal (.por) |
| Document (text-based) | PDF/A-1 / PDF/A-2 (.pdf), ODF (.odt), Plain text (.txt), Markdown (.md), XML (.xml), HTML (.html) | Other PDF, DOC (.doc), DOCX (.docx) |
| Images (raster) | PNG (.png), JPEG (.jpg, .jpeg), JPEG 2000 (.jp2) | TIFF (.tiff, .tif) |
| Images (vector) | SVG (.svg) | |
| Neuroimaging and eye-tracking data (according to BIDS) | BrainVision (.eeg, .vhdr, .vmrk), EDF (.edf), CTF (.ds), DICOM (.dcm), NIFTI (.nii), Eyelink (.edf), SMI (.idf), Plain text (.txt) | |
| Presentations | PDF/A-1 / PDF/A-2 (.pdf), ODF (.odp) | Other PDF, PPT (.ptt), PPTX (.pptx) |
| Spreadsheets, datasets | CSV (.csv), ODF (.ods), TSV (.tab), JSON (.json), XML (.xml) | XLS (.xls), XLSX (.xlsx) |
| Video | OGG (.ogg), MPEG-2 / MPEG-4 (.mpeg), MXF (.mxf), Matroska (.mkv) | AVI (.avi) |
| Version 1.3. Last Updated: October 2025 | ||