Busuu is a combination of thematic courses with the idea of a social platform. The social aspect is used perfectly because the app offers checking for short written forms by native speakers of a given language. Therefore, if you do not have an English friend on hand, you can work with busuu. The minus of the program is paid access to grammar exercises.
If you are an app freak, it's good to use different applications to learning English too. I will show you many handy apps to keep learning English in a few minutes. Furthermore, I will show you many online dictionaries and websites to learn languages.