Duolingo Hard Mode is a free, open-source Chrome extension designed to improve language learning by replacing multiple-choice questions with typing input challenges. This tool emphasizes active recall, which is essential for effective language acquisition. By transforming word bank exercises into text input tasks, it encourages users to engage more deeply with the material and practice their writing skills in the target language.

The extension supports various types of challenges, including translation, gap-fill, tap-complete, and select-transcription, with more features planned for future updates. It seamlessly integrates with Duolingo's original interface, ensuring that users can maintain their familiar learning environment while benefiting from a more rigorous typing-only experience. Overall, Duolingo Hard Mode is an innovative tool for learners seeking to enhance their language skills.