I created this service largely for my own use, as I was tired of relying on third-party services to quickly share some Markdown notes I wrote in Obsidian. Because I believe that others may find this useful, I chose to make it available as a public service.
I have written a detailed blog post about how this service works. You can read it if you want to know more.
If you want to learn further about end-to-end encrypted data transfers on the Web, I highly recommend this talk by Thomas Konrad.