AnkiDroid

AnkiDroid is a semi-official port of Anki, the open-source spaced repetition flashcard system, to Android. It lets people study flashcards on their phones and tablets, with the scheduling logic of spaced repetition deciding when each card is shown again so that material is remembered longer.

The app supports text, images, sounds and MathJax in cards, can sync with AnkiWeb, and includes a whiteboard, night mode, a progress widget and detailed statistics. It offers optional typed answers, text-to-speech integration and the AI-optimized FSRS algorithm for scheduling. More than 10,000 premade decks are available, and cards can be added from other apps, such as dictionaries, through Android intents.

AnkiDroid is written in Kotlin and released under GPL-3.0. Users can consult the user manual and wiki for help, and contributions in the form of beta testing, translation or code are welcome. The README lists a signing certificate fingerprint so that APK downloads can be verified, and credits many translators for broad language coverage.