Firefox Send is a free tool that lets you send encrypted files up to 1GB in size, or 2.5GB if you sign in with a Firefox account.
What sets Send apart is its ease of use. It works in any browser; just go to send.firefox.com. Upload or drag and drop files, and Send will generate a link that you can set to expire after a certain number of downloads—up to 100—or a certain amount of time, ranging from five minutes to seven days.
Being able to use any browser is probably the best part about this tool.