Brief schreiben B1 bis C1 is a free Android app developed by sadotchok, which focuses on helping users improve their German writing skills. The app provides sound, writing, and crucial German vocabulary for all levels of writing, from A1 to C1. It includes model tests that allow users to prepare for their writing exams, and they can also use these tests to evaluate their German language proficiency or practice their language skills.

The app is designed to help users develop their writing skills in German, especially in the areas of writing and reading comprehension. It includes writing tasks, tips for exam preparation, and model tests at different levels, including A2, B1, B2, and C1. Users can also find various letters for different levels, including A2, B1, B2, C1, and C2, all available for free.