After developing a client-side encryption plugin for the Uppy uploader (
https://github.com/0sumcode/uppy-encrypt), I created a proof of concept web app that encrypts files before upload (and decrypts them after download). There are other solutions like this, but I wanted one that was simple, fast, and open-source (
https://github.com/0sumcode/0up) so others can adapt it for any projects that could benefit from it. I hope some folks find the service and/or code helpful!