As of current version 2.3.2, these languages are supported:

 

translation-de.json

translation-en.json

translation-es.json

translation-fr.json

translation-gl.json

translation-pt-BR.json

translation-ru.json

 

For example, for Brazil Portuguese you can use it like this:

DocumentViewer.Language = "pt-BR";

 

If you need to customize a translation or create new translation:

 

Create this folder under your project: App_GlobalResources\WebViewer\Html5\Resources\i18n

And put translation-en.json file (download this file: du-translations.zip), rename this and edit the text for this file to translate to your language. Normally when you do a change under App_GlobalResources, it should be recognized automatically. If not you can force AppDomain restart via touching web.config. Make sure you are using the .NET standard codes for cultures:  http://timtrott.co.uk/culture-codes/

 

Important fix in v2.3.2 (February 16, 2017):

• Fixed: Specific languages like pt-BR (not neutral languages like pt) were not being loaded. New translations under App_GlobalResources\WebViewer\Html5\Resources\i18n were not picked up. Changed the translation file name format from translation-xx_XX.json to translation-xx-XX.json (replaced underscore with dash) so that it exactly matches .NET culture names. DocumentViewer.Language property will now throw an error if set to an invalid .NET culture name.