Google and Apple like to keep you safely inside the walled gardens of their respective app stores, but vaulting over those confining walls is actually pretty easy — as long as you know what you're doing. In this guide, we'll walk you through exactly how to install unauthorised applications in process otherwise known as sideloading.
First of all: You should know the risks. Apps only need to be sideloaded when they aren't officially approved by Google or Apple, and that means you're throwing away all the safety and security their respective approval provides. You need to be very, very sure you trust an app before you allow it on your phone, otherwise you could expose yourself to hacking or phishing threats.
So why is sideloading important? Sometimes you might want to install an app that doesn't meet the rules of iOS and Android; or you might want to join a beta test where only unofficial app packages are available. Most users will never need to sideload an app in their lives, but it can be a handy trick to know.
It's worth repeating though that you should do this at your own risk — you're giving the virtual bouncers employed by Apple and Google the night off and running security yourself. Only sideload an app if you're 100 per cent sure it's not going to do anything untoward with your data or your device.
Sideloading is slightly easier on Android. First, you need to tell the operating system that you're prepared to allow unauthorised apps on your device (apps from "unknown sources" in official parlance). Head to Settings then tap Security and toggle the Unknown sources switch to On.
With that done, you simply need to get an APK (Android Application Package) on your device in whatever way you prefer: you can download it from the web, transfer it via USB, use a third-party file manager app, and so on. Just be very sure you get it from a reputable source, as even genuine APKs can be bundled with unwanted extras.
Launch the APK using your app or file manager of choice and once you've tapped through the standard warning message the app installs itself — from this point on you can use it (and uninstall it) as normal. In most cases the app will auto-update itself as well, although this can vary.
To sideload apps on iOS you need to take advantage of a recent change to the Xcode software. For the uninitiated, Xcode is a free developer app available through the Mac Store. Installing unauthorised apps is a more involved process than it is on Android, and it comes with a few more limitations.
Once Xcode is safely installed on your device, add your Apple ID details under Accounts in the Preferences dialog (in the Xcode menu). You then need to obtain the source code for the app you want to install in iOS: it could be a Game Boy Advance emulator, a display tweaking utility or a weighing app.
Depending on the app, you might need to do some preparatory work, but if a developer is making the source code available then you'll usually find basic instructions included to get it into a form that Xcode can recognise. Use File then Open to open up your app, and select the project on the left.
Connect your iOS device, then from inside Xcode choose Product, Destination and select your device. Give the package a unique name in the Bundle Identifier field (under the General tab), make sure your Apple ID is selected as the team name, and you're just about good to go.
Click the Run button (top left) to compile, load, and run the iOS app on your device. It's not quite as straightforward to follow as the Android approach, and may require some extra work, but it's worth trying for those apps you really want to on your iPhone that aren't listed in the app store.