LuabifyQuick device diagnostics

HTTP/2 & HTTP/3 Test: Check Negotiated Protocol In Your Browser

Click HTTP protocol test See which protocol your browser negotiated for the current page and for a fresh request, then compare the result on your current network.

Protocol snapshot

HTTP/2 and HTTP/3 test

See which HTTP protocol your browser negotiates for requests.

Ready to test

Results reflect the current page and a fresh test request from your browser.

Protocol results

Run the test to detect the active protocol.

Current pageUnknown
Test requestUnknown
Response time--

If HTTP/3 is not shown, your browser, network, or server may not support it yet.

Why run an HTTP/2 and HTTP/3 test online

An HTTP/2 and HTTP/3 test helps you verify which protocol your browser is actually negotiating on the network path you are using right now. That is useful when you are comparing Wi-Fi and mobile data, checking whether a VPN or proxy is affecting protocol negotiation, validating browser support, or confirming whether a CDN or edge path is falling back to HTTP/2 or HTTP/1.1 instead of using HTTP/3.

How the test runs

The page reads the protocol used for the current navigation when available through browser performance data, then makes a fresh request to the protocol-check endpoint and measures which protocol that request negotiated. The result gives you a practical browser-side snapshot of what this session and this path are using, rather than a general claim about every site on the internet.

How to interpret results

If HTTP/3 appears, your browser and current path successfully negotiated QUIC for the tested request. If HTTP/2 appears, the connection is using the modern multiplexed protocol but not HTTP/3 on that path. If the result falls back to HTTP/1.1 or looks different between the page navigation and the test request, browser support, network policy, VPN behavior, caching layers, or edge routing may be affecting protocol negotiation.

  • HTTP/3 means the tested request negotiated QUIC on the current path.
  • HTTP/2 means the request is using the modern multiplexed HTTP/TLS path without HTTP/3.
  • HTTP/1.1 usually means fallback because newer protocol negotiation was not used for that request.
  • Different results between navigation and test request can point to path, cache, browser, or edge differences.
  • Latency here is a simple request timing hint, not a full performance benchmark.

This test reports browser-observed protocol negotiation for the current page and a fresh request to the checker endpoint. It does not prove what every other site supports, it does not grade server configuration, and it does not replace packet-level diagnostics or full CDN audits.

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Frequently Asked Questions

What does this HTTP/2 and HTTP/3 test check?

This test checks which protocol your browser negotiated for the current page and for a fresh request to the protocol-check endpoint. It helps you see what your current browser and network path are actually using right now.

Does this test check protocol support for any website I enter?

No. This page checks the negotiated protocol for the current Luabify session and a fresh request to the checker endpoint. It is a browser-side snapshot of your current path, not a universal validator for arbitrary hosts.

What is the difference between the current page result and the test request result?

The current page result reflects the navigation protocol when the browser exposes it in performance data. The test request result comes from a new request made when you run the test, so differences can reveal path, cache, or negotiation changes.

What does it mean if the test shows HTTP/3?

It means your browser and current network path successfully negotiated QUIC for the tested request. That usually confirms HTTP/3 is working for this browser session on this route.

What if the test shows HTTP/2 instead of HTTP/3?

That means the request used HTTP/2, which is still modern and widely deployed. It may also mean your browser, VPN, proxy, firewall, or the current path did not negotiate HTTP/3 for that request.

Why can the result fall back to HTTP/1.1?

Fallback to HTTP/1.1 can happen when newer protocol negotiation is unavailable on the current path, blocked by middleboxes, affected by browser settings, or not supported by the tested route. It does not automatically mean the whole site is broken.

Can a VPN or corporate network affect HTTP/2 and HTTP/3 results?

Yes. VPNs, proxies, enterprise gateways, and restrictive firewalls can change or limit protocol negotiation, especially for QUIC and HTTP/3. That is why comparing results across different networks is often useful.

Does HTTP/3 always mean better speed?

Not always. HTTP/3 can improve some network conditions, but overall performance still depends on routing, congestion, server behavior, and browser implementation. This page is a protocol check, not a full speed benchmark.

Why do results differ between browsers?

Browsers can differ in HTTP/3 support, feature rollout, security policies, and how they expose performance timing data. The same network can therefore produce different protocol results in different browsers.

Is this HTTP protocol test safe to use?

Yes. It only measures which protocol was negotiated for browser requests to the checker endpoint. It does not require credentials, local network access, or any intrusive browser permission.

What can this HTTP/2 and HTTP/3 test not verify?

It cannot prove what unrelated third-party sites support, grade your server configuration, or provide a full transport-level performance audit. It is focused on browser-observed protocol negotiation for this test path.

When should I use this HTTP/2 and HTTP/3 test online?

Use it when checking whether your current browser and network path negotiate HTTP/3, when comparing Wi-Fi, mobile data, VPN, or office networks, or when you suspect protocol fallback after infrastructure changes. It is also useful as a quick support snapshot.