Useful app to build up your HSK vocabulary and character recognition. Don’t expect magic improvement to happen, but this will solidly bring up your HSK vocab and how it is used in context, which is wayyy better than trying to memorize straight vocab. Think of using this app to improve your vocab so that you can systemically read more difficult texts with gains in listening comprehension / character recognition.
The app is very clean and I like how it displays the highest frequency words first for each HSK level. Gives example sentences with audio for each HSK word. An improvement would be to record everything using a human voice/audio (requires effort, but is extremely useful).