index.md

---

title: PATCH
slug: Web/HTTP/Methods/PATCH
spec-urls: https://www.rfc-editor.org/rfc/rfc5789

---

{{HTTPSidebar}}

The HTTP PATCH request method applies partial modifications to a resource.

PATCH is somewhat analogous to the "update" concept found in {{Glossary("CRUD")}} (in general, HTTP is different than {{Glossary("CRUD")}}, and the two should not be confused).

A PATCH request is considered a set of instructions on how to modify a resource. Contrast this with {{HTTPMethod("PUT")}}; which is a complete representation of a resource.

A PATCH is not necessarily idempotent, although it can be. Contrast this with {{HTTPMethod("PUT")}}; which is always idempotent. The word "idempotent" means that any number of repeated, identical requests will leave the resource in the same state. For example if an auto-incrementing counter field is an integral part of the resource, then a {{HTTPMethod("PUT")}} will naturally overwrite it (since it overwrites everything), but not necessarily so for PATCH.

PATCH (like {{HTTPMethod("POST")}}) may have side-effects on other resources.

To find out whether a server supports PATCH, a server can advertise its support by adding it to the list in the {{HTTPHeader("Allow")}} or {{HTTPHeader("Access-Control-Allow-Methods")}} (for CORS) response headers.

Another (implicit) indication that PATCH is allowed, is the presence of the {{HTTPHeader("Accept-Patch")}} header, which specifies the patch document formats accepted by the server.

Request has body	Yes
Successful response has body	Yes
{{Glossary("Safe/HTTP", "Safe")}}	No
{{Glossary("Idempotent")}}	No
{{Glossary("Cacheable")}}	No
Allowed in HTML forms	No

Syntax

PATCH /file.txt HTTP/1.1

Example

Request

PATCH /file.txt HTTP/1.1
Host: www.example.com
Content-Type: application/example
If-Match: "e0023aa4e"
Content-Length: 100

[description of changes]

Response

A successful response is indicated by any 2xx status code.

In the example below a {{HTTPStatus("204")}} response code is used, because the response does not carry a payload body. A {{HTTPStatus("200")}} response could have contained a payload body.

HTTP/1.1 204 No Content
Content-Location: /file.txt
ETag: "e0023aa4f"

Specifications

{{Specifications}}

See also

• {{HTTPStatus("204")}}

• {{HTTPHeader("Allow")}}, {{HTTPHeader("Access-Control-Allow-Methods")}}

• {{HTTPHeader("Accept-Patch")}} – specifies the patch document formats accepted by the server.