OpenSONAR: a 500 MW reference corpus of Contemporary Written Dutch


SoNaR is a 500-million-word reference corpus of contemporary written Dutch for use in different types of linguistic (incl. lexicographic) and HLT research and the development of applications. The STEVIN funded SoNaR project (2008-2011) built on the results obtained in the D-Coi and Corea projects which were awarded funding in the first call of proposals within the STEVIN programme. SONAR contains over 500 million words (i.e. word tokens) of full texts from a wide variety of text types including both texts from conventional media and texts from the new media. All texts except for texts from the social media (Twitter, Chat, SMS) have been tokenized, tagged for part of speech and lemmatized, while in the same set the Named Entities have been labelled. All annotations were produced automatically, no manual verification took place. The texts are enriched with several annotations (Part of Speech and lemma information) and are available as FoLiA xml files (folia.xml). The system relies on BlackLab server as back-end and WhiteLab as user-interface. OpenSONAR is an online application for exploration of and searching in the SoNaR corpus.



CLARIN National Project

CLARIN centre

Dutch Language Institute

Research domain

Linguistic Subject

Tool task



Tool Type

Research Phase

Tool status

Input Language

Access Contact

Institute for the Dutch Language

Project Contact

Creator Contact


Source code

not specified

Original source


van de Camp, M, Reynaert,MandOostdijk, N. 2017.WhiteLab 2.0: AWeb Interface for Corpus Exploitation. In: Odijk, J and van Hessen, A. (eds.) CLARIN in the Low Countries, Pp. 231–243. London: Ubiquity Press. DOI: License: CC-BY 4.0
de Does, J, Niestadt, J and Depuydt, K. 2017. Creating Research Environments with BlackLab. In: Odijk, J and van Hessen, A. (eds.) CLARIN in the Low Countries, Pp. 245–257. London: Ubiquity Press. DOI: License: CC-BY 4.0
Oostdijk, N., Reynaert, M., Hoste, V., Schuurman, I. (2013) The Construction of a 500 Million Word Reference Corpus of Contemporary Written Dutch in: Essential Speech and Language Technology for Dutch: Results by the STEVIN-programme (eds. P. Spyns, J. Odijk), Springer Verlag.


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