Tandem is for language exchange. You help someone learn Arabic, and they help you learn English. It's free for basic use. Good luck!

In my opinion the best app currently available for learning English is Babbel.com. You actually pay on a monthly basis to use Babbel.com to learn English. But is definitely worth it. If you studied English at Babbel.com and study with a live teacher at italki.com-- that would be a powerful combination. Cheers! www.italki.com/charlesharris

It kind of depends on your level and what aspect of English you want to practice. For example, to practice vocabulary, across all levels, I like Quizlet. For listening, I think the British Council - Elementary Podcasts are pretty good.