Performance Tools
HTTP Version Checker
Detect which HTTP protocol version a website serves (HTTP/1.1, HTTP/2, or HTTP/3).
Enter a domain to detect which HTTP protocol version it serves.
JustChecker tracks your website's performance signals continuously.
Frequently Asked Questions
HTTP/2 allows multiple requests to be multiplexed over a single connection (rather than opening many separate connections) and supports header compression, both meaningfully reducing page load latency, especially for pages with many resources.
Yes - HTTP/3 runs over QUIC (built on UDP rather than TCP), which eliminates a specific performance problem called head-of-line blocking and generally improves performance on unreliable or high-latency networks, like mobile connections.
It usually requires explicit server or CDN configuration to enable HTTP/2 or HTTP/3 - many older setups, or configurations that haven't been revisited recently, remain on HTTP/1.1 by default.
No - this is a transport-layer protocol change handled entirely at the server/CDN configuration level, completely transparent to your application code and content.
While the HTTP/2 specification technically permits plain http, in practice every major browser only implements HTTP/2 over an encrypted https connection - so enabling HTTP/2 effectively requires https already being in place.
Yes - servers negotiate the best protocol version each specific client supports, automatically falling back to HTTP/2 or HTTP/1.1 for clients that don't yet support HTTP/3, so no visitors are excluded.