The Faculty of Humanities and Social Sciences, University of Zagreb (FFZG) has published a croatian stemmer as a Python file. However, it is intended to be used as a command line script for stemming all words within a file.

For my project, I adjusted it to be an nltk-compliant version consisting of a class which has a method stem(). Since the source code was published under LGPL, this is not a problem.

Usage is then as follows: