Browser encoding HTTP requests

Question

What encoding does browser use when sending HTTP requests?

I mean when browser sends the very first request how can it be sure that the encoding it uses will be understood by the server?

Example:

GET /hello.htm HTTP/1.1
User-Agent: Mozilla/4.0 (compatible; MSIE5.01; Windows NT)
Host: www.tutorialspoint.com
Accept-Language: en-us
Accept-Encoding: gzip, deflate
Connection: Keep-Alive

@JulianReschke I mean when sending the HTTP request it must be encoded somehow e.g UTF-8, UTF-16. How does it know encoding can the server decode? — CuriousGuy, Feb 20 '17 at 16:04
@JulianReschke No, I am talking about the HTTP request itself. — CuriousGuy, Feb 20 '17 at 16:50

score 1 · Answer 1 · edited May 23 '17 at 11:46

A browser can tell the server explicitly which encoding is used thanks to Content-type header. Content-type might contains charset, but it's possible to infer the encoding by type. For example, application/json:

Content-type: application/json; charset=utf-8 designates the content to be in JSON format, encoded in the UTF-8 character encoding. Designating the encoding is somewhat redundant for JSON, since the default (only?) encoding for JSON is UTF-8. So in this case the receiving server apparently is happy knowing that it's dealing with JSON and assumes that the encoding is UTF-8 by default, that's why it works with or without the header.

What about the situation that Content-type is not defined in request?

A sender that generates a message containing a payload body SHOULD generate a Content-Type header field in that message unless the intended media type of the enclosed representation is unknown to the sender. If a Content-Type header field is not present, the recipient MAY either assume a media type of "application/octet-stream" ([RFC2046], Section 4.5.1) or examine the data to determine its type.

Browser encoding HTTP requests

1 Answers1