Resources for ALL languages
There is an app called HelloTalk where you can talk to people around the world in the language you are learning. You can do voice messages, texts, calls and videos. Native speakers can correct your grammar and pronunciation. While I have seen (and used) several apps similar to this, HelloTalk is the best I have found. It is extremely useful for those who wish to improve their language skills.
There is also a book called FluentForever by Gabriel Wyner: https://fluent-forever.com/ He is also in the process of making an app which you can support here: https://www.indiegogo.com/projects/the-fluent-forever-app-think-in-any-language-smartphone--2?gclid=Cj0KCQiA6enQBRDUARIsAGs1YQiVvD0X0-l6t9-RETSxgvVcWeS9KPaHG5GdhBgIEOP2rDzTp-_qpLkaApUTEALw_wcB#/