HTTP headers / request & response
Content-Length
Content-Length: 348
What it does
The exact size of the body in bytes. Lets the receiver know when the message ends without closing the connection.
The gotcha
Mismatch with the actual body size causes hangs or truncation; with Transfer-Encoding: chunked it must be absent. 411 means the server insists on it.
Debugging headers on a phone
The fastest way to see what Content-Length 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-Type · Cache-Control · Connection · X-Request-Id
Inspect Content-Length on a live request.
Build the request, send it, read raw headers and timing — from your iPhone. Free to start.