> - Write-only file upload under an obscure domain. A bit dangerous, but a life saver when someone wants to send you a 200MB file. "Just go to frequentrain.com and upload there".

Keep in mind that DNS records, including subdomains, are public. Consider putting the service on a random page instead (e.g. "frequentrain.com/sunnysometimes") and/or using something simple like http basic auth if you're not already.

That said, this is a cool idea and I'll be stealing it :)

The code is all custom and there are no instructions on the page itself, so its very unlikely a stranger would ever find and figure it out. But if it gets popular, that's a good idea!

A few more details if you want to make your own:

- The public page accepts drag and drop anywhere for file upload, and has a text field that uploads its contents immediately upon Ctrl+v. Coupled with a short domain name, it's extremely low friction to upload files or notes from any computer. You can't see what you upload (write-only), so it's not useful to abuse.

- It also opens a Server-Sent Events channel and executes all incoming messages as Javascript code. I use it for redirecting users, sending files, showing text, and pranks. It's only a couple lines of code, massively flexible, and surprisingly reliable.

- The authenticated page can see a list of all uploaded files, along with links to download and delete them. A service worker shows desktop notifications when somebody uploads something.

- Finally, the authenticated page also has a live list of all visitors (SSE channels), with buttons to send them code to execute, or to make them authenticated sessions.

It's the kind of stuff that would horrify me if it was a commercial product, but works marvelously between friends and family.