Free/open-source machine translation software

Article by Mikel L. Forcada appeared on

Here’s a non-exhaustive list of links to existing free/open-source machine translation systems, which I will try to complete as I find about them. To the best of my knowledge, software listed here has:

Rule-based systems

  • Apertium, a free/open-source rule-based machine translation platform.
  • Matxin, a free/open-source rule-based machine translation system for Basque.
  • OpenLogos, a free/open-source version of the historical Logos machine translation system.
  • Anusaaraka, English-Hindi machine translation system.

Statistical machine translation systems


  • Moses, a statistical machine translation system.
  • Marie, an n-gram-based statistical machine translation decoder.
  • Joshua, an open source decoder for statistical translation models based on synchronous context free grammars
  • Phramer, an open-source statistical phrase-based machine translation decoder
  • GREAT, a decoder based on stochastic finite-state transducers, which includes a training toolkit.

Training translation models

  • Giza++ is a tool to train translation models for statistical machine translation (see also the related mkclstool to train word classes)
  • Thot is a toolkit to train phrase-based models for statistical machine translation.

Language models

  • IRSTLM, free/open-source language modelling tool to be used with Moses instead of SRILM, which is not free.
  • RandLM, space-efficient ngram-based language models built using randomized representations (Bloom Filters etc).
  • Kenneth Heafield’s software for the fast filtering of ARPA format language models to multiple vocabularies.


  • Kenneth Heafield’s scripts that make it easy to score machine translation output using NIST’s BLEU and NIST, TER, and METEOR.

Other software

  • RIAis a tool for automatic induction of transfer rules for Transfer-Based Statistical Machine Translation using dependency structures.
  • Chaski: Distributed phrase-based machine translation training tool based on Hadoop.

Example-based machine translation systems

Multi-engine machine translation / system combination

  • MANY: Open Source Machine Translation System Combination.
  • Kenneth Heafield’s multi-engine machine translation system.

Aligners and translation models

  • Giza++: training of statistical translation models.
  • Anymalign,a multilingual sub-sentential aligner.
  • Ventsislav Zhechev’s Sub-tree aligner which can be used for the automatic generation of parallel treebanks.

Web services around machine translation

  • Tradubi is an open-source Ajax-based web application for social translation built upon Apertium (may be tested online).

Distributed machine translation

  • ScaleMT (no release yet, browse at the Apertium Subversion repository) is a free/open-source framework for building scalable machine translation web services.

Other useful tools

… that may be used to build machine translation systems

  • Freeling, a free/open-source suite of language analyzers.
  • Bitextor, an automatic bitext harvester
  • Foma, a finite-state machine toolkit and library
  • HFST, Helsinki Finite State Technology for natural-language morphologies.
  • VISL CG-3, the constraint grammar parser at the Visual Interactive Syntax Learning project of Syddansk Universitet: browse Subversion repository, source snapshots.


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