The HTTP Content-Length header indicates the size, in bytes, of the message body sent to the recipient.
Content-Length is limited in that the message size must be known up front, before sending the headers, which is a problem when content is dynamically generated or streamed.
Transfer-Encoding: chunked for responses sent out in parts as its size is calculated.Content-Length is redundant, because the content length may be inferred from DATA frames. It may still be included for backwards compatibility.| Header type | Request header, Response header, Content header |
|---|---|
| Forbidden request header | Yes |
| CORS-safelisted response header | Yes |
Content-Length: <length><length>The length in octets.