Pixie interface is fully translatable and supports multiple languages that can be switched freely via configuration.

Currently active language can be specified via languages.active config option.

Multiple custom languages can be specified via languages.custom.foo option. Only the lines that you want translated need to be specified, lines that are not specified will fall back to original value.

var pixie = new pixie({
    languages: {
        active: 'spanish',
        custom: {
            spanish: {"filter": "Filtrar", "resize": "redimensionar", "crop": "cultivo"},            
            russian: {filter: 'фильтр', "resize": "изменить размер", "crop": "культура"}, //optional
         }
    }
});
Note:
All available translation lines can be found in translations.json file inside pixie directory. This file only shows available lines, you need to specify translations inside pixie configuration, as shown above. 
Note:
This configuration is located inside index.html file, if using included, default pixie setup.