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/HTTP

POST

The HTTP POST method sends data to the server. The type of the body of the request is indicated by the Content-Type header.

The difference between PUT and POST is that PUT is idempotent: calling it once or several times successively has the same effect (that is no side effect), where successive identical POST may have additional effects, like passing an order several times.

A POST request is typically sent via an HTML form and results in a change on the server. In this case, the content type is selected by putting the adequate string in the enctype attribute of the <form> element or the formenctype attribute of the <input> or <button> elements:

  • application/x-www-form-urlencoded: the values are encoded in key-value tuples separated by '&', with a '=' between the key and the value. Non-alphanumeric characters are percent encoded: this is the reason why this type is not suitable to use with binary data (use multipart/form-data instead)
  • multipart/form-data
  • text/plain

When the POST request is sent via a method other than an HTML form — like via an XMLHttpRequest — the body can take any type. As described in the HTTP 1.1 specification, POST is designed to allow a uniform method to cover the following functions:

  • Annotation of existing resources
  • Posting a message to a bulletin board, newsgroup, mailing list, or similar group of articles;
  • Providing a block of data, such as the result of submitting a form, to a data-handling process;
  • Extending a database through an append operation.
Request has body Yes
Successful response has body Yes
Safe No
Idempotent No
Cacheable Only if freshness information is included
Allowed in HTML forms Yes

Syntax

POST /index.html

Example

A simple form using the default application/x-www-form-urlencoded content type:

POST / HTTP/1.1
Host: foo.com
Content-Type: application/x-www-form-urlencoded
Content-Length: 13

say=Hi&to=Mom

A form using the multipart/form-data content type:

POST /test.html HTTP/1.1 
Host: example.org 
Content-Type: multipart/form-data;boundary="boundary" 

--boundary 
Content-Disposition: form-data; name="field1" 

value1 
--boundary 
Content-Disposition: form-data; name="field2"; filename="example.txt" 

value2

Specifications

Specification Title
RFC 7231, section 4.3.3: POST Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content

Browser compatibility

Feature Chrome Firefox Edge Internet Explorer Opera Safari
Basic Support (Yes) (Yes) (Yes) (Yes) (Yes) (Yes)
Feature Android Chrome for Android Edge mobile Firefox for Android IE mobile Opera Android iOS Safari
Basic Support (Yes) (Yes) (Yes) (Yes) (Yes) (Yes) (Yes)

See also

© 2005–2017 Mozilla Developer Network and individual contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/HTTP/Methods/POST