OnionShare Micah Lee, et al.

OnionShare lets you securely and anonymously share files of any size. It works by starting a web server, making it accessible as a Tor onion service, and generating an unguessable URL to access and download the files. It doesn't require setting up a server on the internet somewhere or using a third party file-sharing service. You host the file on your own computer and use a Tor onion service to make it temporarily accessible over the internet. The other user just needs to use Tor Browser to download the file from you.