Trailer
Both directions
Announces which headers will follow after the body.
| On the wire | Trailer: … |
|---|---|
| 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 Trailer mean?
Announces which headers will follow after the body.
Q. What does Trailer look like on the wire?
It travels as Trailer: …
Q. Where does Trailer appear?
In both directions.
Q. What group does Trailer belong to?
The both directions group; the rest of that group is listed further down.