English Tests AIO is a comprehensive application for those who want to improve their English grammar, vocabulary, and level. It offers over 2300 tests categorized by topic, level, and books, including 85+ categories with sub-categories. The app is perfect for those who want to take placement tests and find their English level from A1 to C2.

The app's features include the ability to resume or retake tests, track finished tests, and report incorrect questions. Users can also set time limits for each question and hide tests they have taken. Additionally, the app has an auto-advance feature that passes the next question automatically.

English Tests AIO is an excellent choice for those who want to improve their English skills in various areas. The app covers grammar, vocabulary, and TOEFL tests and includes content for all levels. Users can also access miscellaneous tests, such as reading comprehension, dialogues, and summarizing, among others.