Vocabulingo is an Vocabulary learn APP connected to your Duolingo account.
Learn a language in Duolingo and study vocabularies in Vocabulingo with the use of index cards.
jwt is short and stands for json web token. You can get this by pasting document.cookie.split('; ').find(row => row.startsWith('jwt')); in your browser console with the open and logged in duolingo main page
This project isn't related to duolingo or any of those products.