Mobile profiles: the iPhone and iPad views

A profile can call itself an iPhone or an iPad to websites. How to turn this on, what changes, and what stays this Mac's.

What a mobile view is

A mobile profile in Lumen is a mobile view: Safari on this Mac calling itself an iPhone or an iPad to websites, in a window the size of that device's screen. Nothing else of the phone or tablet comes with it. Pages are shown by this Mac's WebKit - the engine of its Safari.

This is a real state of Safari: its Develop menu can give it an iPhone's User-Agent in the same way.

Turning it on

Open the profile editor: New Profile, or ⋯ → Edit… in the profile's row.
Under Identity, open View for websites and choose one of:
Mobile view: iPhone, Safari 27 (User-Agent only)
Mobile view: iPhone, Safari 26 (User-Agent only)
iPad view: Safari 26, an iPad-sized window
Click Save. The view applies from the next launch; stop a running profile and launch it again.

The profile list's Appears as column then reads, for example, "Mobile view · Safari 27" or "iPad view · Safari 26". To go back, choose Safari on macOS 26 (matches this engine), the default.

What changes

Two things change: the User-Agent string - in every request's header and in navigator.userAgent - and the window's size.

	iPhone	iPad
User-Agent	Safari on an iPhone: `iPhone OS 18_7`, then `Version/27.0` (Safari 27) or `Version/26.6` (Safari 26)	Safari on a Mac with `Version/26.6`: an iPad asks sites for their desktop version by default and calls itself a Mac
Window	390 × 844 points	820 × 1180 points

18_7 is not a mistake: Safari on iOS 26.1 and later always writes it and names the release only after Version/.
The User agent field below shows the whole string. Its version is fixed in Lumen and does not follow Safari on this Mac; a mobile view has no Safari version in the User-Agent choice.
Custom user agent replaces the string; the window keeps the chosen device's size.
The size is the page area below the toolbar; from the second tab on, the tab bar takes part of it. The window cannot be made wider or taller, and the size under Window does not apply to a mobile view.
Where profiles open in Safari's own window, a mobile view still opens in a Lumen window: Safari's window is a Mac's.

What stays the Mac's

Everything a page can measure, apart from the User-Agent and the window:

the engine: this Mac's features, CSS and JavaScript;
navigator.platform, maxTouchPoints (the touch points) and the number of processor cores;
the screen: its size, colour depth, pixel density and CSS media queries;
touch: there is none - WebKit on the Mac is a desktop engine;
fonts, graphics (WebGL) and audio;
the TLS handshake and the order of headers.

The time zone, language, proxy and every other setting are the profile's own.

Checking it

⋯ → What Sites See… → Take Snapshot. One page of this Mac opens in a window of the profile, then in Safari, and the panel compares what each saw. A mobile view has no reference, and the panel says so: it compares the profile with Safari on this Mac, not with an iPhone, and cannot see the real device's touch, fonts, graphics, audio, motion sensors or screen.

The build's self-test checks an iPhone view: its navigator, screen, touch, rendering and fonts match plain WebKit on this Mac, and only the User-Agent says "iPhone".

What a mobile view cannot do

WebKit's public APIs on the Mac cannot:

declare another screen - a screen-size override exists only in WebKit for iOS;
add touch - WebKit for macOS has no touch emulation;
bring in an iPhone's engine, fonts or graphics.

An iPhone's real signals take Safari on a real iPhone. Lumen has no profile that runs Safari for iOS, with its own engine, fonts and touch.