Content-Length
Both directions
States the size of the body in bytes.
| On the wire | Content-Length: … |
|---|---|
| Category | Both directions |
Headers that can appear on either side.
How to read this
- The first digit of a status code carries the meaning: 4 means the request, 5 means the server.
- 404 means "not there"; 403 means "there, but not for you". Swapping them makes debugging slower.
- Header names are case-insensitive — Content-Type and content-type are the same header.
- Caching and CORS problems usually come down to one header line, visible in the browser’s network tab.
Frequently asked questions
Q. What does HTTP Content-Length mean?
States the size of the body in bytes.
Q. What does Content-Length look like on the wire?
It travels as Content-Length: …
Q. Where does Content-Length appear?
In both directions.
Q. What group does Content-Length belong to?
The both directions group; the rest of that group is listed further down.