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HTTP Browser Header Checker

Introduction to HTTP browser headers

When making HTTP requests for pages over the Internet, a browser sends a number of information header lines to the webserver which will serve that request. Those HTTP information headers do not only contain information about the page that has to be retrieved, but also contain configuration and system information of the browser and of the computer the browser is running on. This information can be used by the webserver to serve the best matching content to the client.

Most Internet users—and also many website builders—are not aware of this extra set of information which accompagnies every request. Proper use of these HTTP headers by webservers can however improve the user experience significantly by matching the response as close as possible to the user and browser preferences. One example is serving webpages in the primary language of the browser. Another example is serving light weight pages when a mobile device is connecting, or send images in the format best processed by that particular browser or output device.

Your HTTP browser headers

HTTP headers sent by your browser
HTTP HeaderContent
User-AgentCCBot/2.0 (
If-Modified-SinceTue, 15 Oct 2019 14:33:36 EDT

Most common HTTP browser headers

Browsers send a variety of HTTP headers. This list contains the most common HTTP headers you will see coming from regular browsers and bots like the crawlers from the major search engines.

Most common HTTP headers sent by browsers
HTTP HeaderDescription
AcceptThis HTTP header contains the MIME types which are accepted by the browser. This can be a list of specific MIME types, but the list may also contains wildcards. The entries in the list are separated by commas. Priority values can be assigned to each MIME type by adding a semicolon followed by a q=val parameter. The priority value val ranges from 0.0 to 1.0 where higher values represent higher priority. In this way the browser can request specific content types, for example JPG files over PNG files if both are available on the server.

Example: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8

Accept-LanguageThe browser sends preferred language information in this HTTP header. The content of the HTTP header is a list of one of more languages. Each language is represented by a two character code like en for English, or a five character code like en-US for American English if a subset of a specific language is requested. Entries in the list are separated by commas. A priority value can be assigned with each language by adding a semicolon followed by a q=val setting. The priority value val may range from 0.0 to 1.0, where 1.0 is the highest priority and 0.0 the lowest.

Example: en,en-us;q=0.7,nl;q=0.3

The ideals which have lighted my way,
and time after time have given me new courage to face life cheerfully,
have been Kindness, Beauty, and Truth.
The trite subjects of human efforts, possessions, outward success, luxury
have always seemed to me contemptible.
  Aug. 2017
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