catsed: relay a file from one machine to another with curl. Nothing is stored.

SEND
  curl -T report.pdf https://catsed.v0lt4.synology.me/
  tar cz dir | curl -T - https://catsed.v0lt4.synology.me/dir.tar.gz      (stdin; name it in the URL, default "data")
  curl -T report.pdf 'https://catsed.v0lt4.synology.me/?wait=2h'          (wait up to 24h for a receiver; default 10m)

  The first line printed is the Transfer URL. Keep the command running: the file
  streams straight to the receiver once they start downloading.
  In scripts, add -N so curl prints the URL immediately:  curl -N -T f https://catsed.v0lt4.synology.me/ | head -1

RECEIVE (single use: the first download wins)
  curl -O https://catsed.v0lt4.synology.me/<code>/report.pdf
  wget https://catsed.v0lt4.synology.me/<code>/report.pdf

NOTES
  - Only curl and wget can receive; browsers and link previews just see this page.
  - Either side disconnecting ends the Transfer; there is no resume.
  - catsed sees your bytes in transit. For end-to-end secrecy, encrypt first:
      age -p report.pdf | curl -T - https://catsed.v0lt4.synology.me/report.pdf.age
  - A server restart closes Transfers still waiting for a receiver; just resend.