A URL Scheme is like “http://…” or “ftp://…”. Those seem like a very low-level concept that you don’t have much control over, but actually, you do!
I’d call it non-trivial, but developers can register new URL schemes in apps that users install. Back in 2017, Microsoft Edge did this:
If you use that, the behavior is to open the URL in Microsoft Edge — even if you’ve chosen a different default browser. So if I, as a blogger, wanted to essentially force you to use Edge for this site, I could, by starting every single URL with this URL scheme. I won’t, but I could. And so could Microsoft.
I don’t hate Microsoft Edge — maybe you do! — but I do believe users who have bothered to configure a different default web browser should be allowed to keep using that default web browser.
This has come back into the public eye a bit as the Brave browser now supports the microsoft-edge:// URL scheme. Apparently, not only does an app need to register a URL scheme, but other apps that support clicks-on-links need to honor it too. Firefox is also thinking of adding it. I think the risk of not supporting the URL scheme is that clicks on links like that could do nothing instead of actually opening the URL.
A lot of the talk is about Windows 11. But here on my Mac, I see this URL scheme do what it intends across all these browsers.
Daniel goes further:
So, how did we get here? Until the release of iOS version 14 in September 2020, you couldn’t change the default web browser on iPhones and iPads. Google has many apps for iOS, including a shell for its Chrome browser. To tie all its apps together, Google introduced a googlechrome: URL scheme in February 2014. It could use these links to direct you from its Search or Mail app and over to Chrome instead of Apple’s Safari browser.
Here’s my iPhone 13 opening googlechrome://css-tricks.com with and without Google Chrome installed.
Seems like that would be Google’s sin, but it is apparently Apple that allowed it on iOS. Daniel once more:
The original sin was Apple’s, but Microsoft is gulping the juice of the apple with gusto.
I’m not as boned up on all this as I should be, but I think if I made software that was involved here, I’d be tempted to intercept these URL schemes and have them open in the browser the user is already in. The web is the web, there should be no reason any given URL has to open in any specific browser.