curl --request POST \
  --url https://api.sandbox.bitwage.com/api/user/document/upload \
  --header 'Authorization: Basic <encoded-value>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "user_id": "<string>",
  "doc_type": "<string>",
  "category": "front",
  "issuing_country": "<string>",
  "base64_image": "<string>",
  "tax_id": "<string>",
  "tax_id_type": "<string>"
}
'

{
  "success": true
}