HTTP/2 & HTTP/3 Protocol Test
Check which HTTP protocols your server supports — HTTP/1.1, HTTP/2, and HTTP/3 (QUIC)
Protocol test checks support for HTTP/1.1, HTTP/2, HTTP/3 (QUIC), TLS 1.2/1.3, ALPN, 0-RTT. Reports Server header, cipher suite, Alt-Svc. Helps diagnose compatibility with modern browsers and CDNs.
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How it works
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Test TLS/HTTP versions
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Why test protocols?
Protocol testing checks which TLS versions the server supports. Legacy versions (TLS 1.0, SSL 3.0) have known vulnerabilities and must be disabled.
TLS Versions
Check TLS 1.0, 1.1, 1.2, 1.3 support — with security rating for each.
Cipher Suites
List of supported cipher algorithms with strength rating for each.
HTTP/2 Support
ALPN negotiation check for HTTP/2 (h2) and HTTP/3 (h3) via QUIC.
Vulnerabilities
Detection of BEAST, POODLE, DROWN, and other TLS/SSL attacks.
Who uses this
DevOps
TLS configuration check
Security
protocol and cipher audit
Developers
HTTP/2 compatibility
SEO
HTTPS ranking signal
Common Mistakes
Best Practices
Monitor SSL certificate automatically
SSL monitor alerts 30 days before expiry and on TLS version changes.
Sign up freeHTTP/2 and HTTP/3 Check
The tool checks HTTP/2 and HTTP/3 (QUIC) protocol support on your server. HTTP/2 provides request multiplexing, header compression (HPACK), and Server Push. HTTP/3 uses QUIC instead of TCP, further reducing latency, especially on mobile networks.
HTTP/2 provides multiplexing, header compression, and server push — typically reducing page load time by 15-30%. HTTP/3 (QUIC) adds 0-RTT connection establishment and improved performance on mobile networks with packet loss. Our tool tests ALPN negotiation and shows which protocols your server actually supports.
After verifying protocol support, check page speed to measure the actual performance impact. Ensure your SSL/TLS configuration supports at least TLS 1.2 — HTTP/2 requires it, and HTTP/3 requires TLS 1.3.
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Frequently Asked Questions
What is the difference between HTTP/2 and HTTP/1.1?
HTTP/2 uses multiplexing (multiple requests over one connection), header compression (HPACK), stream prioritization, and binary format. This significantly speeds up page loading compared to HTTP/1.1.
What is HTTP/3 and QUIC?
HTTP/3 is the latest protocol version, based on QUIC instead of TCP. QUIC eliminates head-of-line blocking, supports 0-RTT connections, and has built-in TLS 1.3. Faster on unstable networks (mobile, Wi-Fi).
How to enable HTTP/2 on a server?
Nginx: add http2 to the listen directive (listen 443 ssl http2). Apache: enable mod_http2 and add Protocols h2 http/1.1. HTTPS is required. Check support with our tool after configuration.
What is multiplexing?
Multiplexing allows sending multiple requests and responses simultaneously over a single TCP connection. In HTTP/1.1, requests are processed sequentially, creating delays. This is the main advantage of HTTP/2.
What is ALPN?
ALPN (Application-Layer Protocol Negotiation) is a TLS extension that allows client and server to negotiate the protocol (h2, http/1.1) during the TLS handshake. Without ALPN, HTTP/2 will not work over HTTPS.
Should I switch to HTTP/3?
HTTP/3 provides advantages on mobile networks and with high packet loss. For most sites, HTTP/2 is sufficient. HTTP/3 is automatically supported through Cloudflare, Fastly, and other CDNs. Check support with our tool.
Related guides
Longer-form reading on this topic from the knowledge base.
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