Lumosity is a free brain training app available for Apple and Android devices. It features daily brain games, workout modes, detailed training insights, and mindfulness training. It is available in several languages.
New York Times Crossword is a free app provides you with the best crossword. It is an entertaining game designed by The New York Times that allows you to enjoy the same crossword printed in this newspaper.
With the Duolingo app, you can practice and improve your speaking, reading, listening and writing skills while playing games at the same time. Just answer questions and complete lessons to improve both your vocabulary and grammar skills.
Today In History is a free app for iOS devices in which you will have access to all kind of daily facts about raw history. It allows you to filter the facts to be based on the tags you are more interested in.
TED is a non-profit organization that focuses on spreading ideas and knowledge typically through short powerful talks from various experts of a given topic or theme. You can catch these talk on their website online or through their mobile apps.