From SweetP Productions:
Xliff Editor provides the easiest way of editing your XLIFF files. No more messing around with the XML format, worrying about file corruption. And you can forget about remembering to save, as every change you make is automatically saved for you. XLIFF files are based on the standard XML format, and are used specifically to exchange localisation data. Xcode 6 introduced the ability to export/import all your localisation data, taking away the need for sending various file formats to your localisers for translating. The XLIFF format makes translating your apps a cinch, as it removes all the layout and formatting, and just provides a simple text to text translation mechanism for your translators.