Picking a flashcard app for iPhone is harder than it should be. The top options all have real trade-offs, and the right answer depends heavily on whether you care more about content libraries, algorithm quality, or how the app actually feels to use on a phone. This is a breakdown of the realistic options, not a ranking based on feature bullet points.
The main contenders are Anki (via AnkiMobile), Quizlet, Brainscape, Mochi, and Gridually. Each one has a genuinely different philosophy about what a flashcard app should do, and those differences matter more on mobile than on desktop because your sessions are shorter and your patience for friction is lower.
One thing worth saying upfront: the best flashcard app for iPhone is whichever one you will actually open during a five-minute wait for coffee. Sophistication means nothing if the interface drives you away after two days.
AnkiMobile gives you the best spaced repetition algorithm available, full offline access, and a massive library of community decks. It costs $24.99 once. Quizlet gives you a polished iOS app, fast card creation, and a huge built-in library, but locks its best study modes behind a $35 annual subscription. If algorithm quality is your priority and you are already comfortable with Anki's interface, AnkiMobile is worth the upfront cost. If you want something fast and frictionless that you can set up in ten minutes, Quizlet's free tier is a decent starting point - just expect to hit limits.
Gridually takes a spatial approach rather than stacking cards in a linear queue. You see a grid of topics, tap into cells, flip through what you know, and the layout makes your blind spots immediately visible. It is free, has proper iOS widgets, and the short-session design suits mobile use better than an app designed for 30-minute desktop study marathons. It is not trying to replace Anki for serious language learners with 10,000-card decks. It is trying to be the app you actually finish a session on. For many iPhone users, that distinction matters more than algorithm depth.
If you have complex, customized decks and need maximum algorithm control: AnkiMobile despite the rough iOS experience. If you want pre-made content for a specific class and do not mind the paywall: Quizlet. If you study in short sessions and want something that feels native to iPhone: Gridually or Mochi. Brainscape is worth considering for professional certification prep specifically - its confidence-based repetition works well for that context. There is no universally best answer, but most iPhone users who are not already committed to Anki will be happier with something designed for mobile from the start.
For pure iPhone use, the apps built with mobile-first design win on daily usability even if they lose on raw feature count. AnkiMobile is the right choice for serious Anki users. Everyone else should try Gridually or Mochi before spending money, because both are free and both are genuinely well-suited to how people actually use their phones. Gridually's spatial encoding is based on memory research from the University of Chicago, University of Bonn, and Macquarie University.
Gridually offers a free iOS experience with spatial memory grids. Quizlet has the most polished iPhone app but is increasingly paywalled. AnkiMobile costs $24.99 but is a one-time purchase with the most powerful spaced repetition. Brainscape has a clean iOS app with certified content.
No. AnkiMobile for iOS costs $24.99. It is a one-time purchase, not a subscription. The desktop and Android versions are free. The iOS price funds development of the open-source project. Gridually and Quizlet both offer free iPhone apps.
AnkiMobile has full offline support after the initial $24.99 purchase. Gridually supports offline study. Quizlet requires Plus ($7.99/month) for offline access. For free offline flashcards on iPhone, Gridually is the strongest option.