Firefox Send uses end-to-end encryption to keep your data secure from the moment you share to the moment your file is opened. It also offers security controls that you can set. You can choose when your file link expires, the number of downloads, and whether you would like to add a password for an extra layer of security.

OnionShare is an open-source tool that lets you securely and anonymously share a file of any size. It works by starting a web server, making it accessible as a Tor onion service, and generating an unguessable URL for you to share so that the recipients can access and download the files.

Magic Wormhole is a package that provides a library and a command-line tool named wormhole, which makes it possible to get arbitrary-sized files and directories (or short pieces of text) from one computer to another. Their motto: "Get things from one computer to another, safely."