Kolędy. Wielki śpiewnik is a free Android app developed by MB4ANDROID under the Education & Reference category. The app includes lyrics to 70 Christmas carols, some of which are accompanied by melodies. The app is designed to revive the tradition of singing Christmas carols together and to remind users of the beauty of the Polish language, melodies, and customs.

The app's interface is simple and straightforward. Users can choose a song from the list of 70 carols and view the lyrics. Some of the songs also include a play button to listen to the melody while following the lyrics. The app also allows users to search for a specific carol and add their favorite songs to a separate list for easy access. Overall, Kolędy. Wielki śpiewnik is a great app for anyone looking to celebrate the holiday season by singing traditional Polish carols.