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A large-scale statistical machine translation system written in Java.

Phrasal: A statistical machine translation system

Phrasal is licensed under the GPL (v3+). For details, please see the file LICENSE.txt in the root directory of this software package.

Copyright (c) 2007-2016 The Board of Trustees of The Leland Stanford Junior University. All Rights Reserved.


We use Gradle to build Phrasal. Gradle will install all dependencies. You need Gradle version 2.1+. If you are on OS X, the easiest way to get Gradle is to install Homebrew and then to type brew install gradle.

Linux / Mac OS X

These instructions assume you are using the bash shell, which is usually the default shell.

  1. Switch to the root of the Phrasal repository and execute: gradle installDist

  2. Set PHRASAL_HOME: export PHRASAL_HOME=`pwd`

  3. Set CLASSPATH: export CLASSPATH=$PHRASAL_HOME/build/install/phrasal/lib/*

  4. (Optional) Build Eclipse project files by executing: gradle eclipse.

  5. (Optional, requires g++, JDK) Build the KenLM loader: gradle compileKenLM.

  6. (Optional, requires g++, JDK, and Boost) Build the KenLM language model estimation tools: gradle compileKenLMtools.


Follow the Linux instructions above. Then be sure to execute gradle startupScripts to generate a .bat file.


If you use Phrasal for research, then please cite the following paper:

 author = {Spence Green and Daniel Cer and Christopher D. Manning},
 title = {Phrasal: A Toolkit for New Directions in Statistical Machine Translation},
 booktitle = {In Proceddings of the Ninth Workshop on Statistical Machine Translation},
 year = {2014}

Documentation / User Guide

See the user guide for complete installation and configuration instructions. The guide also contains a tutorial for building an MT system from raw text.


We have 3 mailing lists for Phrasal, all of which are shared with other Stanford JavaNLP tools (with the exclusion of the parser).

Each address is at

java-nlp-user -- This is the best list to post to in order to ask questions, make announcements, or for discussion among JavaNLP users. You have to subscribe to be able to use it. Join the list via this webpage or by emailing [email protected]. (Leave the subject and message body empty.) You can also look at the list archives.

java-nlp-announce -- This list will be used only to announce new versions of Stanford JavaNLP tools. So it will be very low volume (expect 1-3 message a year). Join the list via via this webpage or by emailing [email protected]. (Leave the subject and message body empty.)

java-nlp-support -- This list goes only to the software maintainers. It's a good address for licensing questions, etc. For general use and support questions, please join and use java-nlp-user. You cannot join java-nlp-support, but you can mail questions to [email protected].