Mnemosyne is an accelerated learning flashcard program that uses the SuperMemo spaced repetition system. Users can create cards containing not just text but also images, sound, movies, and more. It's even possible to embed interactive elements using Javascript. Cards can be categorized into one or more tags, and the tags themselves can be organized into a hierarchy. As a user works through their sets of cards, Mnemosyne collects and summarizes learning statistics illustrating the user's progress. Within an individual study session, users may opt to focus on a subset of cards or enter cramming mode to review a selection of cards as many times as desired. Numerous pre-made Mnemosyne decks can be downloaded from the website. Users may also import cards from Anki, SuperMemo, or CueCard. Mnemosyne's sync protocol can be used to share data across multiple machines. Mnemosyne is available for Windows, macOS, and Linux. Source code can be located on GitHub.