Web

HTTP/2 Test

HTTP/2 Support

Test HTTP/2 support

Enter a domain name to check if HTTP/2 is enabled.

Tool features

Comprehensive HTTP/2 protocol detection
4 checks

HTTP/2 Detection

Check if your website supports HTTP/2 protocol

Performance Benefits

HTTP/2 provides multiplexing, header compression, and improved performance

Modern Protocol

Verify support for HTTP/2 protocol standard

ALPN Support

Check Application-Layer Protocol Negotiation for HTTP/2

What is HTTP/2 & how it works

How modern browsers negotiate a faster connection

HTTP/2 is a major revision of the HTTP protocol that makes web pages load faster. Instead of opening a new connection per request, it multiplexes many requests over a single TLS connection, compresses headers, and lets the server prioritise responses — cutting the round-trips that slow HTTP/1.1 down.

A browser and server agree on HTTP/2 during the TLS handshake using ALPN (Application-Layer Protocol Negotiation). This test opens a connection to the host on port 443, reads which protocol was negotiated, and reports whether HTTP/2 — and HTTP/3, advertised via Alt-Svc — is available.

Multiplexing
Many requests share one connection at once, with no head-of-line blocking.
ALPN
The TLS extension where client and server agree to speak h2.
Alt-Svc
A response header advertising HTTP/3 (QUIC) availability.

How to use this tool

Test a domain's HTTP/2 support in four steps
1
Enter a domain
Type a domain name, e.g. example.com — the host is tested over HTTPS on port 443.
2
Run the test
Click Test HTTP/2 to open a TLS connection and read the ALPN-negotiated protocol.
3
Review protocol support
See which of HTTP/1.1, HTTP/2 and HTTP/3 the host offers, plus the negotiated connection.
4
Read the handshake
Inspect the feature checks and raw handshake to confirm ALPN, Alt-Svc and the response details.

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Frequently asked questions

Common questions about HTTP/2
5 Q&A

HTTP/2 is a revision of HTTP that multiplexes multiple requests over a single connection, compresses headers, and supports server prioritisation — loading pages faster than HTTP/1.1.

Browsers and servers negotiate HTTP/2 during the TLS handshake using ALPN (Application-Layer Protocol Negotiation). If both support h2, the connection uses HTTP/2; otherwise it falls back to HTTP/1.1.

In practice yes. Every major browser only supports HTTP/2 over TLS, so a valid HTTPS certificate is required for HTTP/2 to be negotiated.

HTTP/3 carries the same semantics over QUIC (a UDP-based transport) instead of TCP, removing transport-level head-of-line blocking. Servers advertise HTTP/3 with an Alt-Svc header, which this test also reports.

Most modern servers support it with a directive — for example listen 443 ssl http2 in Nginx, or the http2 module in Apache. Ensure TLS is configured, then enable the HTTP/2 option and reload.