curl --request POST \
  --url https://api.open.cx/media/upload \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: multipart/form-data' \
  --form 'file=<string>' \
  --form 0.file='@example-file'

{
  "id": "<string>",
  "url": "<string>"
}