OmegaT is a free translation memory application written in Java. It is a tool intended for professional translators. It does not translate for you! (Software that does this is called "machine translation", and you will have to look elsewhere for it.) OmegaT has the following features:
Fuzzy matching
Match propagation
Simultaneous processing of multiple-file projects
Simultaneous use of multiple translation memories
User glossaries with recognition of inflected forms
Document file formats include:
XHTML and HTML
Microsoft Office Open XML (Office 2007/2010: .docx, .xlsx, .pptx)
OpenOffice.org
XLIFF (Okapi)
MediaWiki (Wikipedia)
Plain text
Unicode (UTF-8) support: can be used with non-Latin alphabets
Support for right-to-left languages
Integral spelling checker
Compatible with other translation memory applications (TMX)
Interface to Google Translate
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