Are there free alternatives to AirDroid?

Question

Android

The task is simple: transfer many files (mp3) from PC to Android phone. AirDroid was great until (5 minutes later) the free transfer limit ran out. I tried 3 more applications, all turned out to be non-working or too complicated.
I would be very grateful for the advice of an application that will help me.

Answer 1

I put Zender in Eaton - it somehow works, and okay :)

Answer 2

universal - syncting (anywhere as you like win/linux/android/mac/iphone/...)
does not use an intermediate server, transfer directly, over a local network or over the Internet if the target is far away