Language exchange website with open API?

Hi everyone! Two questions for you:
1) Does anybody know/use a language exchange website such as Lang-8 that offers an open API for creating apps and extensions?
2) Have you ever thought of cool ideas that would improve the language exchange website you’re using? What about integrations with WaniKani?

I’m a Lang-8 and HelloTalk user, and I feel that the things I learn through language exchange get lost and I don’t really learn them. Sometimes I try to apply some sort of process (such as getting a correction, extracting a grammar point that I didn’t know, adding it to a “practice” list and then using it in my next diary entry or conversation), but mostly I’m lazy and I don’t do it :3 And then I make the same mistakes again.

You are also invited to “complain” about the language exchange tools you’re using in this other thread (constructive source-of-design complaints :P)