If you're looking for a comprehensive and free German vocabulary trainer, then Learn German Vocabulary Online by MobCrab might just be what you need. With over 15,000 German words and still constantly growing, this app covers the most common nouns with articles, verbs, adjectives, and more, all categorized into over 400 topics. The app is designed for beginners in A1 and A2 levels up to advanced learners in C1 and C2 levels, making it suitable for all kinds of learners.

One of the best features of this app is its intuitive illustrations, which help you memorize new vocabulary faster with high-quality images. You can also listen to professional audio recordings by native speakers, analyze your results, and track your progress with detailed statistics. The app even comes with a review manager, so you can review everything you learn. Plus, you don't need an internet connection to learn, making it perfect for those on the go.