Mobile Apps:

-Chet

-Complete Ear training / complete music reading trainer

-Tonestro violin

-TomeGym: https://www.tonegym.co/

-Tonic

Piano accompaniments:

https://www.youtube.com/watch?v=CigijBabO9Q&list=PLH9w9n5FxbygX8aV8rAOPAcXUp9ZVpl3W

Comment platform:

https://www.disqus.com

Where to find scores:

https://www.8notes.com/

https://imslp.org/