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Keep-Alive

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Keep-Alive provides parameters for persistent HTTP connections – timeout (seconds to keep idle connection open) and max (maximum requests on this connection). It is a hop-by-hop header used with HTTP/1.1's default persistent connections. HTTP/2 and HTTP/3 do not use Keep-Alive – connection persistence is handled at the protocol level.

Keep-Alive: timeout=<seconds>[, max=<count>]

Description

Keep-Alive extends the Connection: keep-alive behavior with configurable parameters. The timeout parameter sets the idle timeout before the server closes the connection. The max parameter limits total requests on the connection. Neither parameter is strictly honored by all servers. In HTTP/2, Keep-Alive is a forbidden header. Apache's KeepAliveTimeout and MaxKeepAliveRequests directives correspond to these parameters.

Examples

Server sets keep-alive
http
HTTP/1.1 200 OK
Connection: keep-alive
Keep-Alive: timeout=5, max=1000

Related

Connection

Specification

RFC 9110 – Keep-Alive specification →