bosstrabs NB I tried Duolingo, it’s a good app but the level doesn’t progress beyond basic really.
As for your question, you’re right in that I don’t think there are (m)any apps which are that helpful in improving your German beyond a basic level, albeit I didn’t spend too much time looking (my German was already beyond duolingo the one time I checked it out anyway).
Rocket German stuff was the best I found out of audio-focused learning guides, and they have an app which comes with its courses, but they’re pretty expensive. I think I only paid for 1 Level before getting tired of it and focusing on other things such as actual in-person classes.
One app I would recommend for German is ‘dict.cc plus’ - download it and pay the $2 or whatever it is to download the full dictionary for offline use and get the full feature set. It’s the quickest and most comprehensive English - German dictionary, and you can save words to a vocabulary list and then play a few memory games with those words.
The only thing it’s lacking is verb conjugation lists. I’ve not yet found a similarly good app for these. I currently just have a free but unspectacular app called ‘German Verbs’ for double-checking these, but there are probably a few fancier apps around with save functions/memory lists if you’re willing to pay.
Finally, not an app, but I’d highly recommend the book ‘Langenscheidt - German Grammar in a Nutshell’ for levels A1-B2. A simple, well-explained guide and reference. Reading it through a few times would definitely be of benefit.
