The HTTP Content-Length header indicates the length of the message body, in bytes.
The Content-Length header is sent as part of a HTTP response to indicate the number of
bytes long the message body is. It can be used by the client to verify that the entire message has been received. Also, for lengthy messages, it can be used to estimate transmission time.
The Content-Length header informs the client of how many
bytes compose the message body of an HTTP response.