I would like to know if many visitors to my sites are using the Arc browser.

It uses a Chrome user agent string: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/ Safari/537.36

Google Analytics does not report any visits from this browser, even when I look at a report that includes millions of users.

When I use Arc and do a Google search for "what is my browser", all of the tools that I find report that I am using Chrome 112.

If this is the same for many Chrome or Chromium based browsers, I wonder how many of them are reported incorrectly by Google Analytics...

So my question: Is there any way, server-side or client-side, to detect if the browser is Arc?

1 Answer 1


Yes! By checking for an Arc-specific CSS variable.

Arc enables us to style a website to match the color palette of the browser UI, by providing us with CSS variables such as --arc-palette-background. Apparently these CSS variables are not available as the page is loading, but are added a little later. Checking for it ion page load consistently fails, but using setTimeout to check it a second later works.

We can check if this CSS variable has been set with this JavaScript code:

    window.addEventListener("load", function() {
            console.log('1 second after window load: ', getComputedStyle(document.documentElement).getPropertyValue('--arc-palette-background') ? 'Yes' : 'No');
        }, 1000);

This is the only way I have found that allows developers to detect if a user is using Arc.

  • You could use this to set up tracking of this information to Google Analytics, for example.
    – Liam
    Commented May 1, 2023 at 16:50

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