croc
Easily and securely send things from one computer to another
... that encompasses all three, without compromising any one of them. A common way to transfer a file is to first upload data to a server, and then, once uploaded, the link is shared with someone who goes to download it. This method is easy, but slow, the transfer rate of the file is half the harmonic mean of the upload and download speeds which makes it slower than either just uploading or downloading.