The Duolingo Solution Viewer is a Firefox extension designed to assist users in their language learning journey. This subscription-based tool provides a comprehensive list of solutions for challenges once answers have been submitted, allowing learners to compare their responses with others. Users can sort solutions by similarity or alphabetically, edit their answers, and pin reference solutions for easy access. It also includes filtering options to refine results based on specific words or phrases.

In addition to its core features, the extension integrates seamlessly with Duolingo's user interface, supporting various themes, including Darklingo++. Keyboard shortcuts enhance usability, enabling quick access to solution windows, forums, and filtering options. While the tool offers extensive functionality, it is important to note that changes to Duolingo's platform may impact its performance, requiring users to stay updated on potential fixes. Overall, this extension is a valuable resource for anyone looking to optimize their learning experience.