The best open source alternative to SDL TRADOS is OmegaT. If that doesn't suit you, our users have ranked more than 25 alternatives to SDL TRADOS and nine of them is open source so hopefully you can find a suitable replacement. Other interesting open source alternatives to SDL TRADOS are Lokalize, Zanata, Gtranslator and LF Aligner.
OmegaT is a free translation memory application written in Java. It is a tool intended for professional translators. It does not translate for you!
It deals with all popular formats and is by far the most complete alternative for SDL
Lokalize is the localization tool for KDE software and other free and open source software. It is also a general computer-aided translation system (CAT) with which you can translate OpenDocument files (*.odt).
Zanata is a web-based system for translators, content creators and developers to manage localisation projects.
GNOME Translation Editor (Formerly known as Gtranslator) is an enhanced gettext po file editor for the GNOME desktop environment. It handles all forms of gettext po files and includes features such as Find/Replace, Translation Memory, different Translator Profiles, Messages...
LF Aligner helps translators create translation memories from texts and their translations. It relies on Hunalign for automatic sentence pairing. Input: txt, doc, docx, rtf, pdf, html. Output: tab delimited txt, TMX and xls. With web features.
Translate terms with Google Spreadsheets, pull strings with a command line tool.
BasicCAT is an open source and free computer-aided translation tool, which aims at providing a simple and useful tool for translators.
Anaphraseus is a CAT (Computer Aided Translation) tool, OpenOffice.org/LibreOffice.org macro set similar to famous Wordfast. It works with the Wordfast Translation Memory format (*.TXT), and supports text segmentation.
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Complete range of tools that matches the ones in trados...