Duolingo is a site and free app similar to Memrise in many ways. You choose languages you want to learn and progress through levels. Duolingo has a bit more variety than Memrise when it comes to activities: it includes chances to speak into your device’s microphone, for example. You can also do a level check before you begin learning, and you can “test out” of certain levels.
I tried it as a native speaker of English who wants to learn German, and I’ve been having fun going through the levels. Unfortunately, there seem to be no courses for native speakers of English who want to learn Japanese … yet.
Here are some screenshots of the mobile app, of Level 1 German for speakers of English:
Then I tried it as a native speaker of Japanese who wants to learn English. There is only one course now, and it’s still in beta. It looks like you can only do this (change your “native” language) on the website, not on the app.
It was actually good practice for my Japanese, too. But I did notice that some of the translations were … well, not very forgiving. For example:
I think my translation is better. It’s more natural to me, anyway. And it certainly isn’t incorrect. On the other hand, when I did the same kind of thing in the English –> German course, it was more forgiving. It said something like, “That’s okay, too.”
Another issue I had with the Japanese –> English course was that some of the sentences were just silly. For example:
Despite these flaws, though, it’s a fun site/app to use. And the site is crowd-sourced translation platform, too, so as more people use it, there should be improvements.