OpenCards is a free award-winning flashcard learning software. The basic idea of OpenCards is to use PowerPoint presentations (*.ppt) or Markdown (*.md) files as flashcard sets. Thereby, slide-titles are represented as questions and the slide contents as their answers. Based on state-of-the-art memorization and scheduling algorithms OpenCards will help you to learn any set of flashcards.

Source: OpenCards

OpenCards can create flash cards from either a PowerPoint file, Markdown file, or from a CSV file. It is open source software, running under macOS, Windows, or Linux. For Chromebook users you will want to look at Flashcard Stash.