Performance Tools
Keep-Alive Checker
Check whether a website supports persistent (Keep-Alive) connections.
Enter a domain to check whether it supports persistent (Keep-Alive) connections.
JustChecker tracks your website's performance signals continuously.
Frequently Asked Questions
Without it, a new TCP connection (with its own handshake overhead) must be established for every single request - Keep-Alive reuses one connection across multiple requests, reducing that repeated overhead and improving load speed, especially for pages with many resources.
HTTP/2 already multiplexes multiple requests over one connection by design, making Keep-Alive somewhat less critical than it was for HTTP/1.1 - but for any HTTP/1.1 traffic still occurring, persistent connections remain meaningfully beneficial.
It's sometimes intentionally disabled to limit the number of simultaneous open connections a server maintains under very high load, trading a small amount of per-request efficiency for reduced server resource consumption.
Each open persistent connection consumes a small amount of server memory while idle - for the overwhelming majority of sites this is a worthwhile trade for the performance benefit, but it becomes a genuine capacity-planning consideration at very high concurrent traffic levels.
The clearest sign is a page with many resources (images, scripts, stylesheets) loading noticeably faster than the sum of establishing that many separate connections would suggest - browser developer tools can show connection reuse directly in the network waterfall.