Mozilla rolled out Firefox Send to test users way back in August 2017, but it seems the feature was popular enough to warrant a full launch. Now, the tool has its own website, which lets you easily send files up to 2.5GB in size (with an account) to your friends, colleagues, or anybody else.
All transfers handled through Send are fully encrypted and are performed by uploading your files to Send and sharing the download link with the appropriate recipients. Send also lets you configure auto-expiry settings for the link.
For example, you can set it to self-destruct after a certain number of downloads or after a pre-determined amount of time has elapsed. If you really want to make sure your files end up in the right hands, you can password protect them, too.
Firefox Send is a free service (for now), so you have nothing to lose by giving it a try. To do so, you visit this link to start uploading your files.