As Gafinha mentioned before, Duolingo is a great option.
Other great application is Mondly: https://www.mondlylanguages.com/
Mondly is a free application. You can have a lesson each day and when you complete the week, you
have a week lesson that tests all you have learned that week.
If you want to do more than one lesson per day, you have to be a premiun user and the payment is
cheap and for only one time.
Mondly application allows you to learn not only one language if not the quantity of languages that you
want to learn.
I guess it has about 33 languages available.
