I had an Apple iPhone 7 Plus until very recently, and I can verify that it works great on that particular iPhone! Make sure you have your iPhone settings configured properly once you download the Firefox App from the App store (After you download it, go to "settings" and scroll down until you see the Firefox app), and make sure you have either wi-fi turned on and cellular data enabled! You can also just Google search "Firefox" on Safari or other web browser, i.e. Chrome, etc., and you can access it from any device that way, if it's not too old, as it won't work on Windows XP or Windows 7, because Windows no longer offers support for those older versions. Hope that helps!