Cards sorted based on test outcomes. Cards are classified into
five proficiency levels. Correctly answered cards are moved one level
to the right, and incorrectly answered cards are moved to the left. 
This neatly separates unknown cards from those you already know.
Efficient card selection mechanism. The matrix-style card selection screen enables you to select cards by set and by proficiency level, in any combination you choose. You have fine-grained control over which cards to include in your next review session.
Card "urgency" indicated through color-coding. Cards are color-coded on a spectrum from green to black based on their test history to indicate how urgently they are in need of review. You always have detailed information about the state of your flashcard deck at your fingertips.
Mathematics with LaTeX. You can use LaTeX to include mathematics on your cards. LaTeX allows you to easily typeset anything from polynomials to differential equations, integrals, symbolic logic, matrices, arrays and numerous other mathematical expressions.
Use images, sounds and video. The app supports embedding of image (*.jpg, *.gif and *.png) and video files (*.mp4), allowing you to include photos, drawings, graphs, diagrams, structure charts, movies, animations, or other visual content on your cards. In addition the app supports audio files (*.wav, *.mp3), which can for example be used to memorize the pronunciations of vocabulary items.
Use spaced repetition. The card selection screen makes it easy
for you to select for repetition precisely those cards that you find most difficult to remember, and skip the ones you already know. 
By
repeatedly selecting cards in lower proficiency levels on the left side
of the screen, cards that you have already mastered will gradually get
excluded from your review sessions, and cards that are difficult for you
will show up with ever-increasing frequency.
No automatic scheduling. Unlike other flashcard apps, there is no algorithm that tries to decide for you which cards you should review. A card scheduling algorithm that is flawed will lead you to spend too much time on cards you already know (and too little on the cards you really need to focus on), which can impair your performance and slow down your progress. With Mindframes, the decision which cards to review is always up to you.
Supports 4-sided cards. 
The app supports flashcards with up to
four sides, If, for example, you are studying Japanese Kanji, you can separately uncover the Kanji
character, the Japanese reading, the Chinese reading, and the English
keyword.
Import your own flashcards. The app supports importing your own flashcard decks in *.csv and *.xlsx format (with a *.zip container used for multimedia decks). Using the import functionality requires an in-app purchase.
Export flashcard decks to files. Save your flashcard decks to
external files that store cards contents, proficiency state, learn
history and deck settings. Make backup copies to protect your flashcard
data, transfer your decks to other devices or share 
them with other
users.
No registration required. Mindframes does not run a back-end server and does not require any registration or login. In-app purchases are processed by Google Play through your Google account.
Works offline. Other than to complete an in-app purchase, no internet connection is required to use the app, so you can practice your cards on the subway, on an airplane, or wherever you go.
Customize your study. Versatile settings enable you to change
the order in which card sides are displayed, select the number of
proficiency levels by which unknown cards are demoted, control the order in which cards are shown 
during review
sessions, change the algorithm for computing card "urgency", and edit
card contents.
If you are Studying Japanese
Mindframes started out as a tool to help students of Japanese memorize the Kanji characters, and a free Jōyō Kanji deck covering all 2,136 characters is still included with the app. For students who would like to build up Japanese vocabulary beyond the Kanji, a customized variant of the app called Mindframes Flashcards Japanese is separately available on Google Play. This separate app includes pre-loaded Japanese vocabulary decks covering more than 50 subject matter areas as in-app purchases. Note that Mindframes Flashcards Japanese does not support LaTeX or multimedia. Mindframes Flashcards Japanese can be obtained here.
Help & FAQ
If you have questions about Mindframes Flashcards, please 
take a look at the Help & FAQ. There is also a separate FAQ for Mindframes Flashcards Japanese, which is available here.
Privacy Notices
To learn how your personal information is handled while you use Mindframes Flashcards, please read the Privacy Notices. The Privacy Notice for Mindframes Flashcards is available here, and the Privacy Notice for Mindframes Flashcards Japanese is available here.
End-User License Agreements
The End-User License Agreement for Mindframes Flashcards is available here, and the End-User License Agreement for Mindframes Flashcards Japanese is available here.