Well, today I decide to write something about three apps that I have been using during this last week for my English learning. Before, I have to mention that these apps are for iOS and I don't know if these apps are for Android devices too.
1. Duolingo
This app is so great!!First of all, you have to decide what kind of schedule you want to do. You can see in the image (I'm so sorry but the horrible screenshoot I made) the time options: 5, 10, 15 or 20 minutes a day, of course I choose the intensive mode of 20 minutes ;).

After that, you can answer a trial test to obtain a general view of your English level.

2. Babbel
This app is very nice!! I consider it very similar to Doulingo because you have to answer different kind of excercises, so at the end you're improving your four basics skills in English language. Obviously, the interface of this app it's different from Duolingo, I mean this app has an interface more conservative (Duolingo is more colorful), but it's a very interesting option!!

3. Wibbu

Finally, this app is very different from the other two. This app is based in a more dynamic way of learning because it's a game!!! You have to follow the adventures of a little girl, so in her travel you can speak with others character and play different kinds of minigames. At the end you're learning English!!

So, these have been the Apps that I have used to develop my English skills. That are good Apps and they're free, so I hope you can enjoy it!!