The default vocabulary tracking on Duolingo was not sufficient for me. I wanted a way to be able to see all the words from my last session and study them to make sure I still know them. I've heard many stories about Duolingo users having finished the entire tree only to find themselves with a very weak vocabulary because they forgot many of the words from the old lessons.
Features: + Query Duolingo to get your list of known vocab + Quiz current list of vocab + Spaced Repetition: Consider the last study time and determine when to study a word again + Supports all five languages
Study Intervals: - One hour - One day - Five Days - One Month - Three Months