旧版書籍用ターゲットの友1400　英単語アプリ is a free, full version iPhone app designed to help students master the 1400-level English vocabulary found in the book "英単語ターゲット1400". Developed by Obunsha Co. Ltd., this app has been used by over 2 million high school students and has received a 98% "recommend to a friend" rating. The app features listening exercises for all 1400 words, a ranking system to compare your progress nationally and by school, and a "today's 5 questions" feature to help establish a daily learning habit. The app also includes an avatar and calendar to make learning fun and enjoyable. In-app purchases are available for additional features such as customizing question patterns and concentrated training on difficult words.