German, as you know, is a grammar-heavy language, requiring painstaking attention to detail from its speakers. LingoDeer is a lesser known app compared to Duolingo or Rosetta Stone, but it is quite popular among those who learn Asian languages, such as Korean and Japanese.
Technology has made learning German easier, more convenient and enjoyable. It allows you to learn German without struggling through boring textbooks and bulky bilingual dictionaries. With a smartphone and Internet connection, you can access German language blogs and top-ranking German podcasts. You can watch German YouTube videos, movies and TV shows on the go. During your commute, you can even listen to German music to hone your language skills. But most likely the easiest and most convenient way are apps to learn German.