Transfer protocol

What we check

We open the home page and look at which protocol the server uses for the transfer:

• HTTP/1.0 or HTTP/1.1: outdated, results in a warning.
• HTTP/2 or HTTP/3: modern, everything is fine.

Why it matters

The protocol is the "language" in which browser and server exchange files. A modern website consists of dozens of files: HTML, stylesheets, scripts, fonts, images.

With HTTP/1.1 the browser can request only one file at a time per connection and therefore opens at most six connections in parallel. All further files have to wait until a line becomes free. With 50 files a jam results.

With HTTP/2 all files are transferred at the same time over a single connection. In addition the headers that go with every request are compressed. Pages with many files load noticeably faster as a result, especially on a smartphone, where every new connection is expensive.

HTTP/3 goes one step further and copes better with dropped connections and dead spots.

HTTP/2 has been the standard since 2015 and is supported by all current browsers. A server that still speaks HTTP/1.1 is usually outdated or set up wrongly.

How to fix it

Hosting

Most hosting providers offer HTTP/2 at no extra charge. With some it has to be switched on in the customer area, with others a request to the support is enough. If the hosting provider does not offer HTTP/2, this is a sign of outdated technology and a good reason to change provider.

Own server

• Apache: activate the module mod_http2 and set Protocols h2 http/1.1 in the configuration.
• nginx: add http2 in the listen line for port 443, or with newer versions set http2 on;.

HTTPS is a prerequisite.

CDN

A CDN such as Cloudflare delivers the website automatically over HTTP/2 and HTTP/3, even if its own server still speaks HTTP/1.1.

Wix, Jimdo, Squarespace

The builders already use modern protocols. There is nothing to do here.

How to check it yourself

Open the developer tools (F12), "Network" tab. Right-click the column headings and show the "Protocol" column. Reload the page: h2 stands for HTTP/2, h3 for HTTP/3, http/1.1 for the old protocol.

Frequently asked questions

Does HTTP/2 need anything special?

Only HTTPS and a current web server. Browsers use HTTP/2 exclusively over encrypted connections. Nothing has to change on the website itself.

Is HTTP/3 even better?

Yes, especially on changeable mobile connections. It is an addition, though: HTTP/2 is the important foundation, HTTP/3 a welcome bonus that many CDNs offer automatically.