Source is an app plus a Safari extension that makes it easy to do one key web developer task: view the HTML source of any web page, with beautiful and customisable syntax highlighting.

Just browse the web in Safari as you normally would, and if you want to view the source for your current page just tap the Action icon and choose Source.

The following steps show you how to get extensions to enhance your browsing experience in Safari on ‌iOS 15‌.

Settings app → Safari → Extensions → toggle on the app or settings.