Hello-Hello

You might've seen apps available by Hello-Hello for exorbitant prices around fifteen dollars. While the only free app they offer is Russian, you can learn all the languages they offer free by just making an account on their website. An app might be nice for learning during travel, but it's much easier to just access the content online :)

German Alphabet Pronunciation

This video is really helpful when you're trying to learn how to pronounce German letters, especially the hard ones like ü or ö.