Being able to import vocabulary from another app would be useful
Thanks a lot for the feature request!
While Wokabulary enables you to add external vocabulary lists (https://support.wokabulary.com/category/18-organizing-vocabulary), we will not be able to directly embed the vocabularies of Duolingo and Babbel, as those are commercial apps creating and selling their content.
However, Quizlet is a nice platform, where people share their vocabularies (and many more learning collections) https://quizlet.com/de.
I am closing this issue, as all words formated in a CSV format (read about the formating here: https://support.wokabulary.com/article/27-csv-file-format-for-importing) can be importted to Wokabulary. We have no influence on if other platforms allow to export their data.