What does Request Desktop Site do?

On both iOS and Android devices, you can press the “request desktop site” button and (usually) get a grossly disproportionate version of the site you’re looking at. But how does this actually work? Is it something to do with media queries?

Absolutely Not

In reality, all that happens is the User Agent string that is sent to the server changes. Let me illustrate with a little diagram. Let’s look at what happens when I request a website from my Macbook:

You can see me (professionally drawn) sending a request to the server. My User Agent string identifies me to the server, and I get a desktop site back.

Now, something very similar happens when I navigate to the same site using a mobile device, such as an iPhone:

All that has changed between these examples is the UA string sent from my device to the server. In the Macbook example, it may look like this:

'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36'

And on my iPhone, like this:

'Mozilla/5.0 (iPhone; CPU iPhone OS 16_6 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/16.6 Mobile/15E148 Safari/604.1'

So, in effect, all that is really happening is the server differentiating the page to send back based on User Agent.

Thanks for joining me on this little dive. And thanks to Stack Overflow for teaching me something new!