OmegaT
OmegaT is a Java-based translation tool that supports many file formats, including XLIFF documents.Open Language Tools - Olanto
The Open Language Tools project provides a Java-based XLIFF editor, along with filters for various file formats.Qt Linguist
Qt Linguist is the translation tool for the Qt environment. It is designed to work with Qt TS files, but supports also PO and XLIFF documents.Virtaal
Virtaal is the translation tool of the Translate Toolkit. It is designed to work with PO files, but can also work with XLIFF documents and a number of other formats.FelixCat XLIFF Translator
(Not open-source, but free) XLIFF Translator is a free XLIFF editor part of the Felix TM system.Lokalize
Lokalize is a KDE application designed as an XLIFF editor. Lokalize can run under Windows with the whole KDE environment installed. The handbook for Lokalize is at: http://docs.kde.org/development/en/kdesdk/lokalize/index.htmlPoedit
Beginning with version 2.2, Poedit also supports the version 1.2 and the new XLIFF 2 format, both in the free and open-source version and the PRO paid version.
Ocelot
Xliffie
Xliff-translator-tool
brightec Online XLIFF Editor (Web App)
www.beyondf.com/tranzapp/translate (Web)