SuperMemo (old)

Great for revising vocabulary, only issue is when you have a list of let’s say 200 words and want to add a new expression you need to manually scroll down the said 200 words to add new element, a bit of a pain

I’ve been using it for years. It requires a lot of patience and willingness. Don't be to enthusiastic. Finishing a course takes a lot of time, especially if you go for the words (each has 3000 words!). In three months (10 new words per day) I will finish (finally and hopefully) english words nrd 4... I can’t even remember how many times I’ve given it up... I bought a lot of courses there, but with no entertainment out of it (it gets boring) and stuck only to English..

In the whole world. But synchronisation after latest update failed, which is a big nuisance making supermemo cloud useless.