Skip to content
Frog is an integration of memory-based natural language processing (NLP) modules developed for Dutch. All NLP modules are based on Timbl, the Tilburg memory-based learning software package.
C++ M4 Other
Branch: master
Clone or download
Fetching latest commit…
Cannot retrieve the latest commit at this time.
Type Name Latest commit message Commit time
Failed to load latest commit information.
docs CLIN 29 Conference poster about Frog added to docs May 6, 2019
include the parser now also handles json servers Sep 9, 2019
m4 attempt to fix libtextcat problems on MaxOSX Nov 28, 2018
src oesp Sep 17, 2019
test leapfrogged Mar 31, 2011
tests makefile cleanup Oct 30, 2018
.gitignore start cleaning up old unused modules Oct 23, 2017
.travis.yml fix .travis.yml Sep 5, 2019
COPYING added codemeta.json to EXTRA_DIST Apr 18, 2018
NEWS get ready for relase 0.18.3 Jul 22, 2019
README added release badge May 6, 2019
TODO First release in the Frog 0.13 series. Sep 28, 2015 start cleaning up old unused modules Oct 23, 2017

Build Status Documentation Status Language Machines Badge DOI GitHub release

Frog - A Tagger-Lemmatizer-Morphological-Analyzer-Dependency-Parser for Dutch

Copyright 2006-2019
Bertjan Busser, Antal van den Bosch,  Ko van der Sloot, Maarten van Gompel

Centre for Language and Speech Technology, Radboud University Nijmegen
Induction of Linguistic Knowledge Research Group, Tilburg University


Frog is an integration of memory-based natural language processing (NLP) modules developed for Dutch. All NLP modules are based on Timbl, the Tilburg memory-based learning software package. Most modules were created in the 1990s at the ILK Research Group (Tilburg University, the Netherlands) and the CLiPS Research Centre (University of Antwerp, Belgium). Over the years they have been integrated into a single text processing tool, which is currently maintained and developed by the Language Machines Research Group and the Centre for Language and Speech Technology at Radboud University Nijmegen. A dependency parser, a base phrase chunker, and a named-entity recognizer module were added more recently. Where possible, Frog makes use of multi-processor support to run subtasks in parallel.

Various (re)programming rounds have been made possible through funding by NWO, the Netherlands Organisation for Scientific Research, particularly under the CGN project, the IMIX programme, the Implicit Linguistics project, the CLARIN-NL programme and the CLARIAH programme.


Frog is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version (see the file COPYING)

frog is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

Comments and bug-reports are welcome at our issue tracker at or by mailing lamasoftware (at) Updates and more info may be found on .


To install Frog, first consult whether your distribution's package manager has an up-to-date package. If not, for easy installation of Frog and its many dependencies, it is included as part of our software distribution LaMachine: .

To be able to succesfully build Frog from source instead, you need the following dependencies:

The data for Frog is packaged seperately and needs to be installed prior to installing frog:

To compile and install manually from source instead, provided you have all the dependencies installed:

$ bash
$ ./configure
$ make
$ make install

and optionally:

$ make check

This software has been tested on:

  • Intel platforms running several versions of Linux, including Ubuntu, Debian, Arch Linux, Fedora (both 32 and 64 bits)
  • Apple platform running macOS

Contents of this distribution:

  • Sources
  • Licensing information ( COPYING )
  • Installation instructions ( INSTALL )
  • Build system based on GNU Autotools
  • Example data files ( in the demos directory )
  • Documentation ( in the docs directory and on )


The Frog documentation can be found on


Many thanks go out to the people who made the developments of the Frog components possible: Walter Daelemans, Jakub Zavrel, Ko van der Sloot, Sabine Buchholz, Sander Canisius, Gert Durieux, Peter Berck and Maarten van Gompel.

Thanks to Erik Tjong Kim Sang and Lieve Macken for stress-testing the first versions of Tadpole, the predecessor of Frog

You can’t perform that action at this time.