HTTP headers / request & response
Content-Type: application/json; charset=utf-8
Declares the media type of the body — what the bytes mean. On requests it tells the server how to parse your payload; on responses it tells your client how to render or decode it.
The #1 cause of 415s and "my JSON arrives as a string": clients default to form encoding or text/plain when you forget to set it.
The fastest way to see what Content-Type is actually doing is to send the request and read both sides raw — ReqPad shows auto-generated and custom headers for every request, on all six protocols, with history. Related references: status codes · Content-Length · Cache-Control · Connection · X-Request-Id
Build the request, send it, read raw headers and timing — from your iPhone. Free to start.