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