What cross-platforms allow you to code software directly under MacOS and Windows?

Question

Programming

Good afternoon!
The task is to find one programmer who will write a program under two axes at once. Or do you need it separately, what language would you recommend?
Here tell me which cross-platform is suitable?
I thought unity, but it doesn’t work very well with video files, or developers, apart from games, don’t write anything in unity.
The purpose of the program:
0) authorizations by api
1) pick up all video files from a folder on your computer
2) the program should sort them by creation date
3) by api from the server to pick up the timing of video pieces for this user
4) from all the videos that are in the folder, select and show the user only those pieces of the timing which are paid by api
5) cut into pieces of the original video
6) the user views, moves in / out of each piece
7) saves these pieces to the computer
6) upload these pieces to the server

Answer 1

Yes, in principle, anything cross-platform will do.
It is possible in Java. It is possible on c ++ (+ Qt naturally). It is possible to pile on a python (and gui, if necessary, on the same pyQt). You can even try in C#.