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Non-standard
This feature is non-standard and is not on a standards track. Do not use it on production sites facing the Web: it will not work for every user. There may also be large incompatibilities between implementations and the behavior may change in the future.
The Keep-Alive general header allows the sender to hint about how the connection and may be used to set a timeout and a maximum amount of requests.
The Connection header needs to be set to "keep-alive" for this header to have any meaning. Also, Connection and Keep-Alive are ignored in HTTP/2; connection management is handled by other mechanisms there.
| Header type | General header |
|---|---|
| Forbidden header name | no |
Syntax
Keep-Alive: parameters
Directives
- parameters
- A comma-separated list of parameters, each consisting of an identifier and a value separated by the equal sign (
'='). The following identifiers are possible:timeout: indicating the minimum amount of time an idle connection has to be kept opened (in seconds). Note that timeouts longer than the TCP timeout may be ignored if no keep-alive TCP message is set at the transport level.max: indicating the maximum amount of requests that can be sent on this connection before closing it. Unless0, this value is ignored for non-pipelined connections as another request will be send in the next response. An HTTP pipeline can use it to limit the pipelining.
Examples
A response containing a Keep-Alive header:
HTTP/1.1 200 OK Connection: Keep-Alive Content-Encoding: gzip Content-Type: text/html; charset=utf-8 Date: Thu, 11 Aug 2016 15:23:13 GMT Keep-Alive: timeout=5, max=1000 Last-Modified: Mon, 25 Jul 2016 04:32:39 GMT Server: Apache (body)
Specifications
| Specification | Title |
|---|---|
| HyperText Transport Protocol Keep-Alive Header | The Keep-Alive Header (Experimental specification) |
| RFC 7230, section appendix-A.1.2: Keep-Alive | Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing |
Browser compatibility
The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.
| Feature | Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | Servo |
|---|---|---|---|---|---|---|---|
| Basic Support | (Yes) | (Yes) | (Yes) | (Yes) | (Yes) | (Yes) | (Yes) |
| Feature | Android | Chrome for Android | Edge Mobile | Firefox for Android | IE Mobile | Opera Mobile | Safari Mobile |
|---|---|---|---|---|---|---|---|
| Basic Support | (Yes) | (Yes) | (Yes) | (Yes) | (Yes) | (Yes) | (Yes) |