Hello. I am currently making an application that need to proceed tickets in background.
I would like to ask about few API methods that I didn't found:
1. Ticket created - how to handle via my app that there is a new ticket were created?
2. Submit internal note - I didn't find any possibility to submit an answer into the ticket, public reply nor internal note.
3. Is the app I'll upload will be always 'online' and listening or it should be done in some way via code?
Kind regards!

Hope you were able to get what you needed but if not, here is a link to our ZAF Client API docs. You should be able to listen for the event of the ticket creation and use client.on in conjunction with the Core Apps API to determine app activation.
Hope this helps!