Preferred FormatsΒΆ

Using general and common file formats is important for ensuring that research data remain accessible and usable in the future. These preferred file formats are ones that are more likely to offer the best long-term guarantees for usability, accessibility and sustainability. It is preferable to use a file format that allows files to be opened with software that is free of charge and universally available. If this is not an option, choose a format that allows files to be opened with software that is commonly used in your research field (Matlab, SPSS and STATA for example). If data are stored in non-preferred formats, there is a risk that other users of your dataset will not be able to open your data files because they would have to pay for the software to do so or because the software no longer exists. The latter may also be a risk for you if you want to use your files in the future.

We therefore encourage you to store files in the Radboud Data Repository (RDR) in a preferred file format listed in the table below. The RDR offers the highest level of preservation on preferred file formats. This means that the RDR strives to not only store the "bits" of the files, but to ensure that the files remain accessible. Accepted formats in the table below are widely used and therefore likely to remain accessible. The RDR does not offer active preservation activities on these files to keep them accessible. Using these formats is therefore riskier. On file formats that are not listed in the table below, the RDR does not make any statements about the associated risks nor offer active preservation activities. Using these formats is not recommended.


Preferred format

Accepted format

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)

Spreadsheets, datasets

CSV (.csv), ODF (.ods), TSV (.tab), JSON (.json), XML (.xml)

XLS (.xls), XLSX (.xslx)


PNG (.png), JPEG (.jpg, .jpeg), JPEG 2000 (.jp2)

TIFF (.tiff, .tif)

Vector images

SVG (.svg)


OGG (.ogg), MPEG-2 / MPEG-4 (.mpeg), MXF (.mxf), Matroska (.mkv)

AVI (.avi)


OGG (.ogg), BWF (.bwf), FLAC (.flac), Wave / WAV (.wav)

MP3 (.mp3)


PDF/A-1 / PDF/A-2 (.pdf), ODF (.odt)

Other PDF, PPT (.ptt), PPTX (.pptx)

Code and analysis scripts

MATLAB (.m), Python (.py), R (.R), SPSS (.dat/.sps), STATA (.dat/.do)

SPSS portal (.por)

CAQDAS (Computer Assisted Qualitative Data Analysis)

RTF (.rtf)

Some software-specific formats such as NUD*IST, Nvivo, ATLAS.ti

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)

Version 1.1. Last updated: October 2023

Is your file type not included? Then ask your data steward or the RDM support team ( for advice.