Helsinki Finite-State Transducer Technology (HFST)


The Helsinki Finite-State Transducer software is intended for the implementation of morphological analysers and other tools which are based on weighted and unweighted finite-state transducer technology. This work is licensed under a GNU Lesser General Public License v3.0.

The feasibility of the HFST toolkit is demonstrated by a full-fledged open source implementation of a Finnish lexicon as well as a number of other languages of varying morphological complexity (OMor).


Scientific publications related to the project, as well as general documentation of the code structure of the software library

» Documentation at KitWiki (

» SourceForge page (


Demos implemented with the HFST code:

» Analyzers, Generators and Guessers


Download area for Open Source tools and interfaces implemented in the project:

» Source Code at SourceForge (

Related Software


» foma Foma finite-state library - for constructing e.g. morphological analyzers with an xfst/lexc-compatible compiler.

» OpenFST OpenFST library for weighted finite-state transducers

» SFST Stuttgart Finite-State Transducer Tools