Description: AnkiDroid is a free and open-source flashcard app for Android. It allows users to create decks of flashcards with text, images, audio, and video, and uses spaced repetition to optimize studying. AnkiDroid can help memorize anything from languages, to science material, to trivia.
Type: software
Pricing: Open Source
Description: Wiktionary is a free, collaborative, multilingual dictionary project operated by the Wikimedia Foundation. It aims to describe all words of all languages using definitions, etymologies, pronunciations, synonyms, and more.
Type: software