HTTP header

Requests

Header	Description	Example
Accept	Content-Types that are acceptable	Accept: text/plain
Accept-Charset	Character sets that are acceptable	Accept-Charset: iso-8859-5
Accept-Encoding	Acceptable encodings	Accept-Encoding: compress, gzip
Accept-Language	Acceptable languages for response	Accept-Language: da
Accept-Ranges	Allows the server to indicate its acceptance of range requests for a resource	Accept-Ranges: bytes
Authorization	Authentication credentials for HTTP authentication	Authorization: Basic QWxhZGRpbjpvcGVuIHNlc2FtZQ==
Cache-Control	Used to specify directives that MUST be obeyed by all caching mechanisms along the request/response chain	Cache-Control: no-cache
Connection	What type of connection the user-agent would prefer	Connection: close
Cookie	an HTTP cookie previously sent by the server with Set-Cookie (below)	Cookie: $Version=1; UserId=JohnDoe
Content-Type	The mime-type of the body of the request (used with POST and PUT requests)	Content-Type: application/x-www-form-urlencoded
Date	The date and time that the message was sent	Date: Tue, 15 Nov 1994 08:12:31 GMT
Expect	Indicates that particular server behaviors are required by the client	Expect: 100-continue
Host	The domain name of the server (for virtual hosting), mandatory since HTTP/1.1	Host: en.wikipedia.org
If-Match	Only perform the action if the client supplied entity matches the same entity on the server. This is mainly for methods like PUT to only update a resource if it has not been modified since the user last updated it.	If-Match: "737060cd8c284d8af7ad3082f209582d"
If-Modified-Since	Allows a 304 Not Modified to be returned if content is unchanged	If-Modified-Since: Sat, 29 Oct 1994 19:43:31 GMT
If-None-Match	Allows a 304 Not Modified to be returned if content is unchanged, see HTTP ETag	If-None-Match: "737060cd8c284d8af7ad3082f209582d"
If-Range	If the entity is unchanged, send me the part(s) that I am missing; otherwise, send me the entire new entity	If-Range: "737060cd8c284d8af7ad3082f209582d"
If-Unmodified-Since	Only send the response if the entity has not been modified since a specific time.	If-Unmodified-Since: Sat, 29 Oct 1994 19:43:31 GMT
Max-Forwards	Limit the number of times the message can be forwarded through proxies or gateways.	Max-Forwards: 10
Pragma	Implementation-specific headers that may have various effects anywhere along the request-response chain.	Pragma: no-cache
Proxy-Authorization	Authorization credentials for connecting to a proxy.	Proxy-Authorization: Basic QWxhZGRpbjpvcGVuIHNlc2FtZQ==
Range	Request only part of an entity.	Range: bytes=500-999
Referer	This is the address of the previous web page from which a link to the currently requested page was followed.	Referer: http://en.wikipedia.org/wiki/Main_Page
TE	The transfer encodings the user is willing to accept.	TE: trailers, deflate;q=0.5
Upgrade	Ask the server to upgrade to another protocol.	Upgrade: HTTP/2.0, SHTTP/1.3, IRC/6.9, RTA/x11
User-Agent	The user agent string of the user agent	User-Agent: Mozilla/5.0 (Linux; X11; UTF-8)
Via	Informs the server of proxies through which the request was sent.	Via: 1.0 fred, 1.1 nowhere.com (Apache/1.1)
Warn	A general warning about possible problems with the entity body.	Warn: 199 Miscellaneous warning

Responses

Header	Description	Example
Accept-Ranges	What partial content range types this server supports	Accept-Ranges: bytes
Age	The age the object has been in a proxy cache in seconds	Age: 12
Allow	Valid actions for a specified resource. To be used for a 405 Method not allowed	Allow: GET, HEAD
Cache-Control	Tells all caching mechanisms from server to client whether they may cache this object	Cache-Control: no-cache
Content-Encoding	The type of encoding used on the data	Content-Encoding: gzip
Content-Language	The language the content is in	Content-Language: da
Content-Length	The length of the response body in 8-bit bytes	Content-Length: 348
Content-Location	An alternate location for the returned data	Content-Location: /index.htm
Content-Disposition	An opportunity to raise a "File Download" dialogue box for a known MIME type	Content-Disposition: attachment; filename=fname.ext
Content-MD5	An MD5 sum of the content of the response	Content-MD5: 3167b9c13ad2b6d36946493fc47976c8
Content-Range	Where in a full body message this partial message belongs	Content-Range: bytes 21010-47021/47022
Content-Type	The mime type of this content	Content-Type: text/html; charset=utf-8
Date	The date and time that the message was sent	Date: Tue, 15 Nov 1994 08:12:31 GMT
ETag	An identifier for a specific version of a resource, often a Message Digest, see ETag	ETag: 737060cd8c284d8af7ad3082f209582d
Expires	Gives the date/time after which the response is considered stale	Expires: Thu, 01 Dec 1994 16:00:00 GMT
Last-Modified	The last modified date for the requested object.	Last-Modified: Tue, 15 Nov 1994 12:45:26 GMT
Location	Used in redirection	Location: http://www.w3.org/pub/WWW/People.html
Pragma	Implementation-specific headers that may have various effects anywhere along the request-response chain.	Pragma: no-cache
Proxy-Authenticate	Request authentication to access the proxy.	Proxy-Authenticate: Basic"
Retry-After	If an entity is temporarily unavailable, this instructs the client to try again after a specified period of time.	Retry-After: 120
Server	A name for the server	Server: Apache/1.3.27 (Unix) (Red-Hat/Linux)
Set-Cookie	an HTTP cookie	Set-Cookie: UserID=JohnDoe; Max-Age=3600; Version=1
Trailer	The Trailer general field value indicates that the given set of header fields is present in the trailer of a message encoded with chunked transfer-coding.	Trailer: Max-Forwards
Transfer-Encoding	The form of encoding used to safely transfer the entity to the user.	Transfer-Encoding: chunked
Vary	Tells downstream proxies how to match future request headers to decide whether the cached response can be used rather than requesting a fresh one from the origin server.	Vary: *
Via	Informs the client of proxies through which the response was sent.	Via: 1.0 fred, 1.1 nowhere.com (Apache/1.1)
Warn	A general warning about possible problems with the entity body.	Warn: 199 Miscellaneous warning
WWW-Authenticate	Indicates the authentication scheme that should be used to access the requested entity.	WWW-Authenticate: Basic

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