Shows common HTTP request and response header names and uses for developers building APIs, debugging browser traffic, or configuring web servers.
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| Header | Meaning | Example |
|---|---|---|
| Accept | Media types the client can process in the response. | Accept: text/plain, text/html |
| Accept-Charset | Character encodings the client accepts. It is obsolete in modern HTTP. | Accept-Charset: iso-8859-5 |
| Accept-Encoding | Content codings the client can decode, such as gzip or br. | Accept-Encoding: compress, gzip |
| Accept-Language | Preferred response languages, optionally weighted with q values. | Accept-Language: en,zh |
| Accept-Ranges | A response header, not normally a request header; it advertises supported range units. | Accept-Ranges: bytes |
| Authorization | Credentials used to authenticate the request to the origin server. | Organisation |
| Cache-Control | Request cache directives, such as no-cache or max-age. | Cache-Control: no-cache |
| Connection | Controls hop-by-hop connection options. It must not be forwarded by proxies. | Connection: close |
| Cookie | Cookies previously stored for the target origin. | Cookie: $Version=1; Skin=new; |
| Content-Length | Size of the request body in bytes. | Content-Length: 348 |
| Content-Type | Media type and optional character encoding of the request body. | Content-Type: application/x-www-form-urlencoded |
| Date | Date and time when the request message was generated; rarely sent by browsers. | Date: Tue, 15 Nov 2010 08:12:31 GMT |
| Expect | Expectations the server must meet, most commonly 100-continue. | Expect: 100-continue |
| From | Optional contact address for the human user controlling the client. Rarely used. | From: user@jsons.cn |
| Host | Target host and optional port. Required in HTTP/1.1 requests. | Host: www.jsons.cn |
| If-Match | Make the request conditional on the current ETag matching one of the supplied values. | If-Match: "Specific value" |
| If-Modified-Since | Return the representation only if it changed after the supplied date. | If-Modified-Since: Sat, 29 Oct 2010 19:43:31 GMT |
| If-None-Match | Make the request conditional on the current ETag not matching a supplied value. | If-None-Match: "Specific value" |
| If-Range | Send a range only when the validator still matches; otherwise send the complete representation. | If-Range: "Specific value" |
| If-Unmodified-Since | Apply the request only if the resource has not changed since the supplied date. | If-Unmodified-Since: Sat, 29 Oct 2010 19:43:31 GMT |
| Max-Forwards | Limits how many proxies may forward a TRACE or OPTIONS request. | Max-Forwards: 10 |
| Pragma | Legacy HTTP/1.0 cache-control field, commonly used as Pragma: no-cache. | Pragma: no-cache |
| Proxy-Authorization | Credentials used to authenticate the request to a proxy. | Proxy-Authorization: Link to proxy authentication |
| Range | Requests one or more byte ranges from the selected representation. | Range: bytes=500-999 |
| Referer | URL of the page that initiated the request. The historical field name is misspelled by specification. | Referer: http://www.jsons.cn |
| TE | Transfer codings the client accepts, plus optional support for trailers. | TE: trailers,deflate;q=0.5 |
| Upgrade | Protocols the client invites the server to switch to on the current connection. | Upgrade: HTTP/2.0, SHTTP/1.3, IRC/6.9, RTA/x11 |
| User-Agent | Identifies the client software making the request. | User-Agent: Mozilla/5.0 (Linux; X11) |
| Via | Lists intermediaries that forwarded the request. | Via: 1.0 fred, 1.1 nowhere.com (Apache/1.1) |
| Warning | Obsolete field for additional cache warnings; removed from current HTTP specifications. | Warning: 199 example.test "Miscellaneous warning" |
| Header | Meaning | Example |
|---|---|---|
| Accept-Ranges | Range units supported by the server, commonly bytes. | Accept-Ranges: bytes |
| Age | Seconds the response has spent in a cache since it was generated or revalidated. | Age: 12 |
| Allow | Request methods supported by the target resource. | Allow: GET, HEAD |
| Cache-Control | Response caching directives, such as max-age, no-cache, private, or no-store. | Cache-Control: no-cache |
| Content-Encoding | Content coding applied to the response body, such as gzip or br. | Content-Encoding: gzip |
| Content-Language | Natural language or languages of the response representation. | Content-Language: en,zh |
| Content-Length | Size of the response body in bytes. | Content-Length: 348 |
| Content-Location | URL for the specific representation contained in the response. | Content-Location: /index.htm |
| Content-MD5 | Obsolete MD5 digest field for the message content. Use Digest or Content-Digest where supported. | Content-MD5: MD5 Validation |
| Content-Range | Byte range carried by a partial response and the complete representation size. | Content-Range: bytes 21010-47021/47022 |
| Content-Type | Media type and optional character encoding of the response body. | Content-Type: text/html; charset=utf-8 |
| Date | Date and time when the origin server generated the response. | Date: Tue, 15 Nov 2010 08:12:31 GMT |
| ETag | Opaque validator identifying the selected representation version. | ETag: "Request variable entity label current value" |
| Expires | Date and time after which a cached response is considered stale. | Expires: Thu, 01 Dec 2010 16:00:00 GMT |
| Last-Modified | Date and time when the origin believes the resource was last changed. | Last-Modified: Tue, 15 Nov 2010 12:45:26 GMT |
| Location | URL used for redirects or to identify a newly created resource. | Location: http://www.jsons.cn |
| Pragma | Legacy HTTP/1.0 cache field. Cache-Control is preferred in modern responses. | Pragma: no-cache |
| Proxy-Authenticate | Authentication scheme and parameters required by a proxy. | Proxy-Authenticate: Basic |
| refresh | Non-standard refresh instruction supported by some browsers. Prefer an HTTP redirect where appropriate. |
Refresh: 5; url= http://www.jsons.cn
|
| Retry-After | When the client should retry, expressed as a date or a delay in seconds. | Retry-After: 120 |
| Server | Information about the origin server software. Detailed version disclosure can increase fingerprinting risk. | Server: Apache/1.3.27 (Unix) (Red-Hat/Linux) |
| Set-Cookie | Creates or updates a cookie in the user agent. | Set-Cookie: UserID=JohnDoe; Max-Age=3600; Version=1 |
| Trailer | Names fields that may appear in the trailer section of a chunked message. | Trailer: Max-Forwards |
| Transfer-Encoding | Hop-by-hop transfer coding used to frame the message, commonly chunked in HTTP/1.1. | Transfer-Encoding:chunked |
| Vary | Request fields a cache must consider when selecting a stored response. | Vary: * |
| Via | Lists intermediaries that forwarded the response. | Via: 1.0 fred, 1.1 nowhere.com (Apache/1.1) |
| Warning | Obsolete field for additional cache warnings; removed from current HTTP specifications. | Warning: 199 Miscellaneous warning |
| WWW-Authenticate | Authentication scheme and challenge parameters required by the origin server. | WWW-Authenticate: Basic |