Green Line Vokabeltrainer is a mobile application designed for iPhone users to enhance their English vocabulary skills efficiently. This educational tool operates offline and utilizes a scientifically-based 7-stage model, allowing users to learn vocabulary in manageable portions over an extended period. The app's intelligent algorithm automatically reminds users when it's time to review specific vocabulary, ensuring long-term retention of learned words.

The training process is divided into three clear phases: Memorization, Practice, and Testing. Users can create their own lessons, purchase ready-made ones, and form study groups to share vocabulary. Additional features include an integration with the PONS Online Dictionary for easy vocabulary transfer, performance statistics, and a calendar mode for targeted test preparation. Registration provides access to the PONS Vocabulary Cloud, enabling synchronization across devices.