The cruel joke of Duolingo English Test prep: the language app and the test share a name, and yes, the app actually helps. Daily streaks keep you in English mode, and the bite sized lessons fit a commute. But the test itself is a different animal. It's short, it's adaptive, and it punishes small mistakes, so your prep needs to be focused, not sprawling.
Anki on Android is excellent, genuinely free, with endless shared decks for academic vocabulary. The Duolingo test loves precise vocabulary in its writing and speaking tasks, and Anki is how you build that precision. Quizlet's Android app hands you shared Duolingo English Test flashcard sets that other students already made, so you're not building decks from scratch. Good. Steal their work.
Then the piece everyone skips: Google Calendar. The test can be taken any time, which sounds convenient right up until you realize it means you keep postponing it. Put a test date in the calendar, count back eight weeks, and block daily practice. An IELTS prep app with streaks on iOS and Android is about motivation. The calendar is about commitment. Different thing.
One Android specific tip, and I mean this: do your speaking practice out loud, into your phone, in a quiet room. The test's speaking tasks are recorded and auto scored, so mumbling into your pillow doesn't count as practice. Record yourself, play it back, cringe, improve. That loop is the whole game.
Apps cover the daily reps. Somebody still has to decide what you practice each week. The 8-week study plan at internationalstudyhelp.fyi makes those decisions for you.