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OmegaT

Summary

A free and open-source, cross-platform Computer Assisted Translation (CAT) tool with fuzzy matching, translation memory, keyword search, glossaries, and translation leveraging into updated projects. Licensed under GPL v3.

Overview

OmegaT is one of the oldest and most established open-source CAT tools, originally created by Keith Godfrey around 2000 and maintained by a community of 40+ contributors. It is written in Java (93.2%), making it cross-platform (Windows, Mac, Linux, Solaris, FreeBSD).

Core Features

  • Fuzzy matching — finds similar but not identical translations in memory
  • Translation Memory (TM) — stores previous translations for reuse
  • Keyword search — searches across translation memory and glossaries
  • Glossaries — term-base support for consistent terminology
  • Translation leveraging — when source files are updated, existing translations are preserved and marked for review
  • Machine translation integration — Google Translate, DeepL, Azure Translate via plugins
  • Spell checking — built-in spell checker for target language
  • Extensive file format support — .po, .properties, .html, .xml, .xlsx, .docx, .idml, OpenOffice, and many more via filters

Architecture Highlights

  • Modular design — Gradle multi-project build with bundled plugins as parallel modules
  • Component-based — each component implements a specific interface (IEditor, IProject, IMatcher, etc.)
  • Event-driven — CoreEvents system for loose coupling between components
  • Swing UI — Java Swing-based graphical interface
  • Plugin system — .jar files with manifest entries, supporting filters, tokenizers, markers, machine translators, glossaries
  • SRX segmentation — uses SRX (Segmentation Rules eXchange) standard for sentence boundary detection

Build System

  • Gradle with concurrent multi-project compilation
  • JDK 11+ for building, Java 8+ compatible runtime
  • installDist for full distribution assembly
  • Containerized builds for platform-specific installers
  • Smart task execution — Gradle skips unchanged parts

Team

  • Jean-Christophe Helary — Project manager
  • Hiroshi Miura — Lead developer
  • Briac Pilpré — Webmaster
  • Kos Ivantsov — Localisation manager
  • Philippe Tourigny — Documentation manager

Ecosystem

  • omegat.org — Official website
  • omegat-plugins — Certified plugins database
  • plugin-skeleton — Plugin development starter
  • SourceForge — Legacy hosting, bug tracker, feature requests
  • Read the Docs — Developer documentation